Fluid-expandable body articulation of catheters and other flexible structures

ABSTRACT

Articulation devices and methods include balloon arrays interacting with elongate skeletal support structures so as to locally alter articulation of the skeleton. The skeleton may include a helical coil, and the array can be under control of a processor. Inflation fluid may be directed to the balloons from an inflation system including valves controlled by the processor. The articulation structures can be employed in minimally invasive medical catheter systems.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of priority from co-assignedU.S. Provisional Patent App. Nos. 62/139,430 filed Mar. 27, 2015,entitled “Articulation System for Catheters and Other Uses”; 62/175,095filed Jun. 12, 2015, entitled “Selective Stiffening for Catheters andOther Uses”; 62/248,573 filed Oct. 30, 2015, entitled “FluidArticulation for Catheters and Other Uses”; 62/263,231 filed Dec. 4,2015, entitled “Input and Articulation System for Catheters and OtherUses”; and 62/296,409 filed Feb. 17, 2016, entitled “Local Contractionof Flexible Bodies using Balloon Expansion for Extension-ContractionCatheter Articulation and Other Uses”; the full disclosures which areincorporated herein by reference in their entirety for all purposes.

The subject matter of the present application is related to that ofco-assigned U.S. patent application Ser. No. 15/080,979 filedconcurrently herewith, entitled “Fluid Drive System for CatheterArticulation and Other Uses”; and to that of co-assigned U.S. patentapplication Ser. No. 15/081,026 also filed concurrently herewith,entitled “Articulation Systems, Devices, and Methods for Catheters andOther Uses”; the full disclosures which are also incorporated herein byreference in their entirety for all purposes.

FIELD OF THE INVENTION

In general, the present invention provides structures, systems, andmethods for selectively altering the bend characteristics of elongatebodies, the lengths of such bodies, and the like. Embodiments of theinvention may be used to reversibly, locally, and/or globally alter thestiffness (such as to stiffen or reduce the stiffness of) elongateflexible bodies used for medical and other applications. The inventionmay include or be used with articulation structures, systems, andmethods for articulation, as well as for controlling and fabricatingarticulation structures. In exemplary embodiments the invention providesarticulated medical systems having a fluid-driven balloon array that canhelp steer and advance a catheter, guidewire, or other elongate flexiblestructure along a body lumen. Also provided are structures forfacilitating access to and/or alignment of medical diagnostic andtreatment tools with target tissues, articulation fluid control systems,and medical diagnostic and treatment related methods. Alternativeembodiments make use of balloon arrays for articulating (or altering thestiffness of) flexible manipulators and/or end effectors, borescopes,prosthetic fingers, robotic arms, positioning supports or legs, consumerproducts, or the like.

BACKGROUND OF THE INVENTION

Diagnosing and treating disease often involve accessing internal tissuesof the human body. Once the tissues have been accessed, medicaltechnology offers a wide range of diagnostic tools to evaluate tissuesand identify lesions or disease states. Similarly, a number oftherapeutic tools have been developed that can help surgeons interactwith, remodel, deliver drugs to, or remove tissues associated with adisease state so as to improve the health and quality of life of thepatient. Unfortunately, gaining access to and aligning tools with theappropriate internal tissues for evaluation or treatment can represent asignificant challenge to the physician, can cause serious pain to thepatient, and may (at least in the near term) be seriously detrimental tothe patient's health.

Open surgery is often the most straightforward approach for gainingaccess to internal tissues. Open surgery can provide such access byincising and displacing overlying tissues so as to allow the surgeon tomanually interact with the target internal tissue structures of thebody. This standard approach often makes use of simple, hand-held toolssuch as scalpels, clamps, sutures, and the like. Open surgery remains,for many conditions, a preferred approach. Although open surgicaltechniques have been highly successful, they can impose significanttrauma to collateral tissues, with much of that trauma being associatedwith gaining access to the tissues to be treated.

To help avoid the trauma associated with open surgery, a number ofminimally invasive surgical access and treatment technologies have beendeveloped. Many minimally invasive techniques involve accessing thevasculature, often through the skin of the thigh, neck, or arm. One ormore elongate flexible catheter structures can then be advanced alongthe network of blood vessel lumens extending throughout the body and itsorgans. While generally limiting trauma to the patient, catheter-basedendoluminal therapies are often reliant on a number of specializedcatheter manipulation techniques to safely and accurately gain access toa target region, to position a particular catheter-based tool inalignment with a particular target tissue, and/or to activate or use thetool. In fact, some endoluminal techniques that are relatively simple inconcept can be very challenging (or even impossible) in practice(depending on the anatomy of a particular patient and the skill of aparticular physician). More specifically, advancing a flexible guidewireand/or catheter through a tortuously branched network of body lumensmight be compared to pushing a rope. As the flexible elongate bodyadvances around first one curve and then another, and through a seriesof branch intersections, the catheter/tissue forces, resilient energystorage (by the tissue and the elongate body), and movement interactionsmay become more complex and unpredictable, and control over therotational and axial position of the distal end of a catheter can becomemore challenging and less precise. Hence, accurately aligning theseelongate flexible devices with the desired luminal pathway and targettissues can be a significant challenge.

A variety of mechanisms can be employed to steer or variably alterdeflection of a tip of a guidewire or catheter in one or more lateraldirections to facilitate endoluminal and other minimally invasivetechniques. Pull wires may be the most common catheter tip deflectionstructures and work well for many catheter systems by, for example,controllably decreasing separation between loops along one side of ahelical coil, braid, or cut hypotube near the end of a catheter or wire.It is often desirable to provide positive deflection in opposeddirections (generally by including opposed pull wires), and in manycases along two orthogonal lateral axes (so that three or four pullwires are included in some devices). Where additional steeringcapabilities are desired in a single device, still more pull wires maybe included. Complex and specialized catheter systems having dozens ofpull wires have been proposed and built, in some cases with each pullwire being articulated by a dedicated motor attached to the proximalend. Alternative articulation systems have also been proposed, includingelectrically actuated shape memory alloy structures, piezoelectricactuation, phase change actuation, and the like. As the capabilities ofsteerable systems increase, the range of therapies that can use thesetechnologies should continue to expand.

Unfortunately, as articulation systems for catheters get more complex,it can be more and more challenging to maintain accurate control overthese flexible bodies. For example, pull wires that pass through bentflexible catheters often slide around the bends over surfaces within thecatheter, with the sliding interaction extending around not only bendsintentionally commanded by the user, but also around bends that areimposed by the tissues surrounding the catheter. Hysteresis and frictionof a pull-wire system may vary significantly with that slidinginteraction and with different overall configurations of the bends, sothat the articulation system response may be difficult to predict andcontrol. Furthermore, more complex pull wire systems may add additionalchallenges. While opposed pull-wires can each be used to bend a catheterin opposite directions from a generally straight configuration, attemptsto use both together—while tissues along the segment are applyingunknown forces in unknown directions—may lead to widely inconsistentresults. Hence, there could be benefits to providing more accurate smalland precise motions, to improving the lag time, and/or to providingimproved transmission of motion over known catheter pull-wire systems soas to avoid compromising the coordination, as experienced by thesurgeon, between the input and output of catheters and other elongateflexible tools.

Along with catheter-based therapies, a number of additional minimallyinvasive surgical technologies have been developed to help treatinternal tissues while avoiding at least some of the trauma associatedwith open surgery. Among the most impressive of these technologies isrobotic surgery. Robotic surgeries often involve inserting one end of anelongate rigid shaft into a patient, and moving the other end with acomputer-controlled robotic linkage so that the shaft pivots about aminimally invasive aperture. Surgical tools can be mounted on the distalends of the shafts so that they move within the body, and the surgeoncan remotely position and manipulate these tools by moving input deviceswith reference to an image captured by a camera from within the sameworkspace, thereby allowing precisely scaled micro-surgery. Alternativerobotic systems have also been proposed for manipulation of the proximalend of flexible catheter bodies from outside the patient so as toposition distal treatment tools. These attempts to provide automatedcatheter control have met with challenges, which may be in-part becauseof the difficulties in providing accurate control at the distal end of aflexible elongate body using pull-wires extending along bending bodylumens. Still further alternative catheter control systems apply largemagnetic fields using coils outside the patient's body to directcatheters inside the heart of the patient, and more recent proposalsseek to combine magnetic and robotic catheter control techniques. Whilethe potential improvements to control surgical accuracy make all ofthese efforts alluring, the capital equipment costs and overall burdento the healthcare system of these large, specialized systems is aconcern.

In light of the above, it would be beneficial to provide improvedarticulation systems and devices, methods of articulation, and methodsfor making articulation structures. Improved techniques for controllingthe flexibility of elongate structures (articulated or non-articulated)would also be beneficial. It would be particularly beneficial if thesenew technologies were suitable to provide therapeutically effectivecontrol over movement of a distal end of a flexible guidewire, catheter,or other elongate body extending into a patient body. It would also bebeneficial if the movement provided by these new techniques would allowenhanced ease of use; so as to facilitate safe and effective access totarget regions within a patient body and help achieve desired alignmentof a therapeutic or diagnostic tool with a target tissue. It would alsobe helpful if these techniques could provide motion capabilities thatcould be tailored to at least some (and ideally a wide) range ofdistinct devices.

BRIEF SUMMARY OF THE INVENTION

The present invention generally provides new articulation devices,systems, and methods for articulation and for fabricating articulationstructures. The structures described herein will often include simpleballoon arrays, with inflation of the balloons interacting with elongateskeletal support structures so as to locally alter articulation of theskeleton. The balloons can be mounted to a substrate of the array, withthe substrate having channels that can direct inflation fluid to asubset of the balloons. The skeleton may comprise a simple helical coil,and the array can be used to locally deflect or elongate an axis of thecoil under control of a processor. Inflation fluid may be directed tothe balloons from an inflation fluid reservoir of an inflation system,with the inflation system preferably including valves controlled by theprocessor. Such elongate flexible articulation structures can beemployed in minimally invasive medical catheter systems, and also forindustrial robotics, for supporting imaging systems, for entertainmentand consumer products, and the like. As the articulation array structuremay be formed using simple planar 3-D printing, extrusion, and/ormicromachining techniques, the costs for producing structures havinglarge numbers of kinematic degrees of freedom may be much, much lowerthan those associated with known powered articulation techniques.

The present invention also provides new devices, systems, and methodsfor selectively, locally, and/or reversibly altering the bendcharacteristics of an elongate body. Bending of an elongate body isaddressed in detail herein, and some of the technologies describedherein are also suitable for altering the stiffness along an elongatecatheter body, with the stiffness often being altered by inflation ofone or more balloons. A number of different stiffening approaches may meemployed. Optionally, inflation of a balloon can induce engagementbetween the balloon and the loops of a helical, cut-tube, braided, orother elongate flexible skeleton, so that the balloon may act as a brakeor latch to inhibit flexing. The balloon will often be eccentricallymounted relative to the skeleton, and may be included in a balloonarray. Selective inflation of a subset of the balloon array canselectively and locally increase axial stiffness of the overall body. Inother embodiments, modulating a balloon inflation pressure can allow theballoon to variably counteract a compressive force of a helical coil orother biasing structure, effectively modulating the overall stiffness ofan assembly. In still other embodiments, independently modulatingpressure of two opposed balloons can be used to both impose a bend orelongation and to modulate a stiffness in at least one orientation.Hence, stiffening and bending or elongation balloons can be combined,using either separate balloon arrays or a multifunctional array havingdiffering types of balloons.

In a first aspect, the invention provides an articulatable bodycomprising a multi-lumen helical shaft having a proximal end, a distalend, and an axis therebetween. The shaft defines an axial series ofloops and having a plurality of lumens. A plurality of balloons isdistributed along the loops, each balloon having a balloon wallextending around the shaft. A plurality of ports opens into the shaft,each port providing fluid communication between an associated balloonand an associated lumen.

The balloons will often be configured so that inflation of the balloonswill, in use, alter a bending state of the articulatable body. Thearticulatable body may include six or more, nine or more, or even 12 ormore balloons, and typically comprises a catheter but may alternativelycomprise an industrial continuum robotic structure, a consumer orentertainment device, or the like. Optionally, a first subset of theballoons is distributed along a first loop and a second subset of theballoons is distributed along a second loop; a plurality of additionalsubsets may be distributed along other loops. In those or otherembodiments, a third subset of the balloons can be offset from the axisand aligned along a first lateral orientation, and a fourth subset ofthe balloons can be offset from the axis and aligned along a secondlateral orientation offset from the axis and from the first lateralorientation. The ports associated with the third subset of balloons maybe in fluid communication with a first lumen of the shaft, and the portsassociated with the fourth subset of balloons may be in fluidcommunication with a second lumen of the shaft. The third and fourthsubsets will often include balloons of the first, second, and othersubsets, and yet another subset of the balloons can be offset from theaxis and aligned along a third lateral orientation offset from the firstand second lateral orientations.

The balloons typically define an M×N array, with M lateral subsets ofthe balloons being distributed circumferentially about the axis, each ofthe M lateral subsets including N balloons aligned along an associatedlateral orientation. For example, M may be three or four, so that thereare three or four lateral subsets of balloons distributed about the axisof the articulatable body (the centers of the subsets optionally beingseparated by 120 or 90 degrees). The ports associated with the balloonsof each of the M lateral subsets may provide fluid communication betweenN balloons and an associated lumen, so that each of the lateralorientations is associated with (often being inflated and/or deflatedvia) a particular lumen of the shaft. The array will often comprise afirst array extending along a first segment of the articulatable body.The first segment can be configured to be driven in two, three, or moredegrees of freedom by fluid transmitted along the lumens associated withthe M lateral subsets of the first array. A second segment of thearticulatable body can also be provided, typically axially offset fromthe first segment. The second segment can have a second array and can beconfigured to be driven in a plurality of degrees of freedom by fluidtransmitted along lumens of the shaft associated with the second array,which will often be separate from those of the first array.Articulatable bodies may have from 1 to 5 independently articulatablesegments or more, with each segment preferably providing from one tothree degrees of freedom, each segment often being configured to haveconsistent bend characteristics and/or elongation between its proximalend and distal end, but the different segments being driven to differentbend and/or elongation states.

The balloon walls will often comprise a non-compliant balloon wallmaterial. Alternatively (or in addition), the balloon walls may comprisea semi-compliant balloon wall material. Advantageously, the balloons mayhave cross-sections that are sufficiently small and/or thicknesses thatare sufficiently large to allow inflation to pressures that may behigher than standard medical balloons of similar materials, for example,allowing easily fabricated balloons having semi-compliant balloon wallmaterials to be inflated above 5, 10, or even 20 atm, with someembodiments capable of withstanding even higher balloon pressures (suchas when environmental loads are applied and the deflation valve isclosed, which may induce loads of 50 atm or more). Preferably, theballoons comprise a continuous balloon wall tube sealingly affixedaround the shaft at a plurality of seals. The seals can be separatedalong the shaft axis so that the tube defines the balloon walls of theplurality of balloons. The balloon wall tube can have a plurality ofballoon cross-section regions interleaved with a plurality of sealcross-section regions, the balloon cross-section regions being largerthan the seal cross-section regions to facilitate fluid expansion of theballoons away from the shaft. Optionally, a reinforcement band can bedisposed over the balloon adjacent the seal so as to inhibit separationof the balloon from the shaft associated with inflation of the balloon.Suitable reinforcement bands may comprise a metal structure similar to amarker band that is swaged over the balloon tube and shaft along theseal, a fiber that is wound on, or the like. Typically, an elongatestructural skeleton will support the multi-lumen shaft, the skeletonhaving pairs of interface regions separated by axial offsets, theoffsets changing with flexing of the skeleton, wherein the balloons aredisposed between the regions of the pairs.

In another aspect, the invention provides an articulatable bodycomprising an elongate flexible skeleton having a proximal end and adistal end and defining an axis therebetween. The skeleton has pairs ofinterface regions separated by offsets; the offsets change with flexingof the skeleton. A substrate can be mounted to the frame, and aplurality of balloons can be supported by the substrate. The balloonscan be distributed axially and circumferentially about the skeleton, andcan be disposed between the regions of the pairs. A channel system maybe disposed in the substrate so as to provide fluid communicationbetween the proximal end of the frame and the balloons.

Optionally, the substrate has first and second opposed major surfacesand a plurality of layers extending along the major surfaces. Thechannel system can be sealed by bonding layers of the substratetogether. The substrate can be curved in a cylindrical shape, forexample, by rolling a substrate/balloon assembly after it has beenfabricated in a planar configuration. A plurality of valves can bedisposed along the channels so as to provide selective fluidcommunication between the proximal end and the balloons. Optionally, theballoons can have balloon walls that are integral with a first layer ofthe substrate, such as by blowing at least a portion of a shape of theballoon from the layer material.

The substrate often comprises a helical multi-lumen shaft. The balloonarray optionally comprises an M×N array of balloons supported by thesubstrate, with M being three or four such that three or four subsets ofballoons are distributed circumferentially about the axis. Each of the Msubsets can aligned along an associated lateral orientation offset fromthe axis. N may comprise 2, such that each of the M subsets includes twoor more axially separated balloons.

In another aspect, the invention provides a method for making anarticulatable structure. The method comprises providing a multi-lumenshaft having a proximal end and a distal end with a shaft axistherebetween. A plurality of lumens can extend along the shaft axis.Ports can be formed into the lumens, the ports being disposed within aplurality of balloon regions. The balloon regions can be separated alongthe shaft axis. A balloon wall tube can be provided, with the balloontube having a proximal end and a distal end with a lumen extendingtherebetween. The shaft can be sealed within the lumen of the balloontube at a plurality of seals between the balloon regions so as to form aplurality of balloons. The shaft axis may comprises a helix having aplurality of loops and the balloons can be disposed on a plurality ofseparate loops.

Conveniently, the shaft axis can be straight during the sealing of theshaft within the lumen of the balloon tube. Hence, the shaft may be bentwith the balloon tube to form a helical shaft. Alternatively, the shaftmay be slid into the lumen of the balloon tube after bending the shaftin some embodiments.

In another aspect, the invention provides a method for articulating anarticulatable body. The method comprises transmitting fluid along aplurality of lumens of a helical multi-lumen shaft, with the shaftdefining a series of loops. A plurality of balloons is inflated with thetransmitted fluid. The balloons are distributed along the loops, eachballoon having a balloon wall extending around the shaft. The inflatingof the balloons is performed by directing the fluid radially from thelumens through a plurality of ports so that each port provides fluidcommunication between an associated lumen and an associated balloon.

In yet another aspect, the invention provides a method for articulatingan articulatable body. The method comprises transmitting fluid along achannel system disposed in a substrate. The substrate is mounted to anelongate flexible skeleton and supports a plurality of balloons. Theelongate flexible skeleton has pairs of interface regions separated byaxial offsets, and the balloons are disposed between the regions of thepairs. The fluid is directed to the balloons with the channel system sothat a subset of the balloons expand. The balloons are distributedaxially and circumferentially about the skeleton and are disposed in theoffsets. The expanding of the subset of balloons changes a bend state ofthe skeleton.

The loops will often have proximal interface regions and distalinterface regions. The balloons may comprise expandable bodies, and theballoons that are between loops may be disposed between a distalinterface of the first associated loop and a proximal interface of thesecond associated loop, the proximal and distal interfaces definingpairs of interfaces and having offsets therebetween. The balloons mayoptionally be mounted over a third loop of the coil between the firstand second loops, or on an additional helical structure having loopsbetween the loops of the helical coil. The helical coil may be includedin a skeleton of the articulation system.

In some embodiments, the substrate may comprise a flexible multi-lumenshaft or tubular body, optionally including an extruded polymermulti-lumen tube with the channels being defined by the extruded lumenstogether with micromachined radial ports; the multi-lumen tubular bodyideally bending to follow a helical curve. The skeleton may beintegrated into such a multi-lumen helical body, disposed within such amulti-lumen helical body, or interleaved with such a multi-lumen helicalbody. The actuation array may also include a plurality offluid-expandable bodies distributed across and/or along the substrate.The expandable bodies can be coupled with associated pairs of theinterfaces, and the channels can provide fluid communication between theexpandable bodies and the fluid supply system so as to facilitateselective inflation of a subset of the expandable bodies.Advantageously, the expandable bodies can be operatively coupled to theoffsets so that the selective inflation alters articulation of theskeleton adjacent the subset.

In exemplary embodiments, the skeleton may comprise a tubular series ofloops, such as when the skeleton is formed from a helical coil, a braid,a hypotube or other medical-grade tubular material having an axialseries of lateral incisions or openings so as to provide more lateralflexibility than a continuous tube would have, or the like. Each pair ofinterfaces may comprise, for example, a first associated surface regionof a first associated loop and a second associated surface region of asecond associated loop adjacent the first loop, so that inflation of theexpandable bodies can alter flexing of the skeleton between the loops.For example, the balloons of the array may be supported by a pluralityof helical multi-lumen shafts, with the substrate comprising themulti-lumen shafts. Alternatively, the substrate may comprises a singlemulti-lumen shaft, and wherein the frame comprises a tubular structurehaving loops separated by axial struts, the pairs of regions comprisingapposing surfaces of the loops. Note that expandable bodies that arecoupled to a pair of interfaces may optionally be coupled to only thepair of interfaces (so that inflation of that structure does not largelyalter flexing of the skeleton between other loops), but that in otherembodiments the expandable body may be coupled with not only the pair ofloops but with one or more additional loops so that flexing of theskeleton may be altered over an axial portion extending beyond the pair.As an example, an elongate balloon may extend axially along an inner orouter surface of several loops, so that when the balloon is inflatedbending of the coil axis along those loops is inhibited.

In embodiments where at least some of the expandable bodies or balloonsare coupled with pairs of interfaces, the first interfaces of the pairsmay optionally be distally oriented and the second interfaces of thepairs may be proximally oriented. The relevant expandable bodies can bedisposed axially between the first and second interfaces. Expansion ofeach of these expandable bodies may urge the associated loops of suchpairs apart, often so that the skeleton adjacent the associated firstand second loops bends laterally away from the expanded balloon. Alateral orientation of the bend(s) relative to the skeletal axis may beassociated with the location of the expandable bodies relative to thataxis. A quantity or angle, an axial location, and/or a radius of thearticulation or bend imposed by any such inflation may be associatedwith characteristics of the expandable body or bodies (and theassociated changes in offset they impose on the skeleton due toinflation), with characteristics of the skeleton, with location(s) ofthe expandable body or bodies that are expanded, and/or with a numberand density of the bodies expanded. More generally, bend characteristicsmay be selected by appropriate selection of the subset of expandablebodies, as well as by the characteristics of the structural componentsof the system.

At least some expandable bodies or balloons of the array (or of anotherseparate articulation array) may be mounted to the skeleton or otherwiseconfigured such that they do not force apart adjacent loops to imposebends on the axis of the skeleton. In fact, some embodiments may have nofluid-expandable structure that, upon expansion or deflation but withoutan external environmental force, induces bending of the skeleton axis atall. Similarly, one or more of the expandable bodies or balloons of theactuation arrays described herein may optionally be used to locally andreversibly alter strength or stiffness of the skeleton, in someembodiments weakening the skeleton against bending in a lateralorientation at desired axial location. In one particular example, wherethe skeleton comprises a resilient helical coil in which a pair ofadjacent coils are resiliently urged against each other by the materialof the coil, a balloon (or set of balloons) disposed axially between onepair of loops of the coil (or a set of loops) may be inflated to apressure which is insufficient to overcome the compressive force of thecoil, but which will facilitate bending of the coil under environmentalforces at the inflated pair (or pairs). More generally, inflation of asubset of balloons may locally weaken the coil so as to promote bendingunder environmental forces at a first location, and changing the subsetmay shift the weak location (axially and/or circumferentially) so thatthe same environmental stress causes bending at a different location. Inother embodiments, the interfaces may, for example, include a firstpair, and a first interface of the first pair may be radially oriented.Similarly, a second interface of the first pair may be radiallyoriented, and a first expandable body may be radially adjacent to andextend axially between the first and second interfaces of the first pairso that expansion of the first expandable body axially couples the firstexpandable body with the first and second interfaces of the first pair.This axial coupling may result in the first expandable body supportingthe relative positions of the interfaces of the pair, inhibiting changesto the offset between the interfaces of the first pair and helping tolimit or prevent changes in bend characteristics of the axis of theskeleton adjacent the first pair when the expandable body is expanded.Advantageously, if such an expandable body is expanded when the axis islocally in a straight configuration, the expandable may prevent it frombending; if such an expandable body is expanded when the axis is locallyin a bent configuration, it may prevent the axis from straightening.

In any of the articulation systems described above, the pairs mayinclude a first pair of the interfaces offset laterally from the axisalong a first lateral axis. An associated first expandable body may bedisposed between the interfaces of the first pair. In such embodiments,a second expandable body may be disposed between a second pair of theinterfaces that is offset laterally from the axis along a second lateralaxis transverse to the first lateral axis. Hence, inflation of thesecond expandable body may bend the axis of the skeleton away from thesecond lateral axis and inflation of the first lateral body may bend theaxis of the skeleton away from the first lateral axis. In otherembodiments, a second pair of the interfaces may be offset laterallyfrom the axis and may be opposed to the first lateral axis and to thefirst pair so that the axis extends between the first pair and thesecond pair, such that inflation of a second expandable body disposedbetween the second pair together with the first expandable body urgesthe skeleton to elongate axially. In still other embodiments, a secondexpandable body may be disposed between a second pair of the interfaces,with the second pair axially offset from the first pair and sufficientlyaligned along the first lateral axis with the first pair so thatinflation of the first expandable body urges the skeleton to bendlaterally away from the first lateral axis, and inflation of the secondexpandable body together with the first expandable body urges theskeleton to bend laterally further away from the first lateral axis. Ofcourse, many embodiments will include multiple such combinations ofthese structures and capabilities, with a plurality of pairs being alonglaterally offset, a plurality being opposed relative to the axis, and/ora plurality being axially aligned so that by inflating appropriatesubsets of the expandable bodies (as disposed between associatedpluralities of pairs of interface surfaces or structures), the axis canbe bent laterally in a single orientation by different incrementalamounts, the skeleton can be axially lengthened by different incrementalamounts, and/or the axis can be bent laterally in a plurality ofdifferent lateral orientations by differing incremental amounts, allsequentially or simultaneously. Combinations of any two or more of thesedesired structures and capabilities can be provided with the relativelysimple structures described herein.

The expandable bodies may optionally comprise non-compliant balloonwalls, and each expandable body can have an expanded configurationdefined by expansion with a pressure within a full expansion pressurerange, and an unexpanded configuration. The offsets of the skeleton canhave associated open and closed states, respectively. The skeleton(and/or structures mounted thereto) will optionally be sufficientlybiased to urge the axial offsets toward a closed state when the balloonsare in the unexpanded configuration and no environmental loads areimposed.

The skeletons and arrays of the above embodiments will often be includedin a catheter configured for insertion into a body of a patient. Thearticulation systems for medical or non-medical uses may also include aninput configured for receiving a catheter articulation command from auser, and a processor coupling the input to the fluid supply source. Theprocessor may be configured to selectively direct the fluid to a subsetof the expandable bodies in response to the command. Embodiments ofthese systems may operate in an open-loop manner, so that the actualarticulation actuation is not sensed by data processing components ofthe system and feed back to any processor. Other embodiments may includecircuitry to generate feedback signals indicative of the state of someor all of the balloons or offsets. Optionally, a plurality of the valvesmay be coupled to the proximal end of the skeleton. Instead (or inaddition), a plurality of the valves may be disposed along the array.For example, the substrate of the array may comprise first and secondsubstrate layers with a substrate layer interface therebetween, and thechannels may comprise channel walls extending into the first layer fromthe substrate interface.

The expandable bodies of any of the arrays described herein may bedistributed axially and circumferentially along the substrate, so thatthe array may define (for example) an at least two dimensional array.Actuation fluid containment sheathing may encase the skeleton andballoons, with the sheathing optionally being integrated with thesubstrate. This may allow used inflation fluid to flow proximally fromthe balloons outside the channels of the substrate and therebyfacilitate balloon deflation without releasing the used inflation fluidinside a body or the like.

Prior to use, the array will often be coupled with a skeleton structureso that expansion of the expandable bodies alters an axis of theskeleton. Typically, the flexible substrate will be flexed from aninitial shape during mounting of the array to the skeleton, and may alsobe further flexed during articulation of the skeleton by the array.

Optionally, the skeleton may include a helical coil, which may havespaces between the loops when in a relaxed state or the coil may insteadbe biased so that adjacent loops of the coil axially engage each otherwhen the coil is in a relaxed state, which can help to transmit axiallycompressive loads between the loops. Alternative skeletons may includehypotube or other tubing having a plurality of lateral slots so as todefine the loops there between, and/or a braided tubular structurehaving a plurality of braid elements defining the loops.

The skeleton often comprises a plurality of circumferential loops of ahelical coil, the coil including a helical axis winding around the axisof the skeleton, and the balloons include at least one balloon walldisposed around the helical axis along at least a portion of anassociated loop of the coil. The associated pair of regions may bedisposed on adjacent loops of the coil, so that inflation of the balloonmay push both adjacent loops away from the loop on which the balloon ismounted. Advantageously, a plurality of balloons may be formed from acontinuous tube of material over a helical core by intermittentlyvarying the size of the material outward (such as by blowing thematerial using balloon forming techniques) or inward (such as byintermittently heat shrinking the material) or both. The core mayinclude one or more balloon inflation lumens, and by appropriatepositioning of the balloons along the helical axis, appropriate sizing,shaping, and spacing of the balloons, and by proving ports through awall of the core into a lumen associated with each balloon, the balloonarray may be fabricated with limited cost and tooling.

The fluid channel system will often comprise one or more helical lumenextending along one or more helical axis of one or more helicalstructures. For example, a first plurality of the balloons can be offsetfrom the axis along a first lateral orientation and in fluidcommunication with the helical lumen, the helical coil comprises a firsthelical coil. A second helical coil may be offset axially from andcoaxial with the first helical coil, the second helical coil havingsecond loops interspersed with the loops of the helical coil along theaxis of the catheter or other elongate body. The second helical coil mayhave a second helical lumen in fluid communication with a secondplurality of the balloons offset from the axis along a second lateralorientation so that transmission of fluid along the first and secondhelical lumens deflects the skeleton along the first and second lateralorientations, respectively.

In some embodiments, the fluid channel system comprises a second helicallumen extending along the helical axis. A first plurality of theballoons may be offset from the axis along a first lateral orientationand in fluid communication with the first helical lumen, and a secondplurality of the balloons may be offset from the axis along a secondlateral orientation and in fluid communication with the second helicallumen. This can allow transmission of fluid along the first and secondhelical lumens of the same helical coil to deflect the axis along thefirst and second lateral orientations, respectively.

An optional feature of the structures provided herein is that thearticulation devices may have balloon arrays with at least 9, 18, 36,72, or even 108 balloons. Where the articulated catheter has an outercross-sectional diameter, the balloon array may have an axial density ofat least 3, 4, 6, 8, or even 9 balloons per diameter of axial length toprovide, for example, a desirable bend capability. The manifold/catheterinterface may provide an axial density of at least 1, 2, 3, 4, or even 6channels per diameter of axial length of the receptacle. Havingstructural features, including small profile seals between balloons andbetween relatively high-density, high pressure channels within thecatheter/manifold quick-disconnect interface structures maysignificantly impact the utility of the system.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified perspective view of a medical procedure in whicha physician can input commands into an catheter system so that acatheter is articulated using systems and devices described herein.

FIG. 1-1 schematically illustrates a catheter articulation system havinga hand-held proximal housing and a catheter with a distal articulatableportion in a relaxed state.

FIGS. 1A-1C schematically illustrate a plurality of alternativearticulation states of the distal portion of the catheter in the systemof FIG. 1.

FIG. 2 schematically illustrates an alternative distal structure havinga plurality of articulatable sub-regions or segments so as to provide adesired total number of degrees of freedom and range of movement.

FIG. 3 is a simplified exploded perspective view showing a balloon arraythat can be formed in a substantially planar configuration and rolledinto a cylindrical configuration, and which can be mounted coaxially toa helical coil or other skeleton framework for use in the catheter ofthe system of FIGS. 1 and 2.

FIGS. 4A and 4B are a simplified cross-section and a simplifiedtransverse cross-section, respectively, of an articulatable catheter foruse in the system of FIG. 1, shown here with the balloons of the arrayin an uninflated, small axial profile configuration and between loops ofthe coil.

FIG. 4C is a simplified transverse cross-section of the articulatablecatheter of FIGS. 4A and 4B, with a plurality of axially alignedballoons along one side of the articulatable region of the catheterinflated so that the catheter is in a laterally deflected state.

FIG. 4D is a simplified transverse cross-section of the articulatablecatheter of FIG. 4, with a plurality of laterally opposed balloonsinflated so that the catheter is in an axially elongated state.

FIG. 5 schematically illustrates components for use in the cathetersystem of FIG. 1, including the balloon array, inflation fluid source,fluid control system, and processor.

FIG. 5A is a simplified schematic of an alternative balloon array andfluid control system, in which a plurality of valves coupled with theproximal end of the catheter can be used to direct fluid to any of aplurality of channels of the array and thereby selectably determine asubset of balloons to be expanded.

FIGS. 5B and 5C schematically illustrate simplified multi-layeredballoon array substrates defining channels, associated fluid controlvalves, and valve-control leads or channels, for use in the cathetersystem of FIG. 5.

FIGS. 6A and 6B are simplified transverse cross-sections of alternativearticulatable catheter structures having a balloon array substratedisposed radially outwardly from a helical coil skeleton, and having aballoon array substrate disposed radially between inner and outerhelical coils, respectively.

FIG. 6C is a simplified transverse cross-section of an articulatablecatheter for use in the system of FIG. 1, wherein balloons each radiallyengage a plurality of loops of a helical coil of a catheter skeleton soas to inhibit bending of a catheter axis.

FIG. 6D is a schematic of a balloon array and valve system for use inthe catheter of FIG. 6C so as to selectably and locally inhibit bendingalong one or more desired axial portion of the catheter.

FIGS. 6E-6H are schematic illustrations showing exemplary balloon arraystructures and interactions between balloons and other components ofexemplary assemblies for selectively and locally stiffening flexiblecatheters and other elongate bodies.

FIGS. 6I and 6J are a simplified plan schematic and perspectiveillustration, respectively, showing an alternative actuation arraystructure having tabs that can be displaced radially from a cylindricalsubstrate surface shape, and with balloons on the tabs.

FIG. 6K is a simplified transverse cross-section of an alternativecatheter structure having material or a body disposed between a balloonand a helical surface so as to provide desirable interface surfaceshapes, and also shows a sheath to radially contain any releasedinflation fluid and/or to apply an axially compressive load to theskeleton and balloons.

FIG. 6L is a simplified transverse cross-section of yet anotheralternative catheter structure in which the skeleton includesreceptacles for receiving expandable bodies therein so as to inhibitrelative migration between the expandable bodies and skeleton, and tounintended axial deflections; and also shows a pull wire to activelyapply controllable axial loads to the skeleton and balloons.

FIGS. 6M-6P schematically illustrate exemplary balloons, balloon arraystructures, and methods for making balloon arrays for use in thearticulation and/or stiffening systems described herein.

FIGS. 7A-7F schematically illustrate valve and balloon arrangementswhich may be used and/or combined in the inflation fluid supply systemsof the systems and devices described herein.

FIGS. 7G-7I schematically illustrate a simple alternative balloon arraystructure in which the substrate is coiled helically, and in whichballoons and channels are formed separately and affixed between layersof the substrate.

FIG. 8 schematically illustrates a catheter articulation system in whichan input of the system is incorporated with an introducer sheath.

FIG. 9 shows a helical coil with inflated and uninflated balloons of aballoon array, with a distal portion of the coil removed to show thediffering lateral orientations of the balloons relative to the axis ofthe coil.

FIGS. 10A-10D are perspective drawings showing an exemplary flat-patternsubstrate and associated balloon array generated by unwinding a helicalballoon pattern, along with an exemplary bonded balloon fabricationtechnique.

FIG. 10E illustrates an alternative bonded balloon arrangement.

FIGS. 10F-10I schematically illustrate balloon structures andfabrication techniques for use in the balloon arrays described herein.

FIGS. 11A and 11B schematically illustrate balloon arrays in which theballoons are disposed over multi-lumen helical coil cores, shafts, orconduits, and also show the effects of varying balloon inflation densityon a radius of curvature of a catheter or other flexible body.

FIGS. 11C and 11D schematically illustrate structures having a pluralityof interleaved coaxial helical coils.

FIGS. 11E-11G schematically illustrate balloons disposed over a helicalcore at differing lateral orientations, and also show how extrudedand/or micromachined multi-lumen helical cores can be used to providefluid communication between and/or inflate one or more associatedballoons at desired lateral orientations on a common core.

FIG. 12 is an exploded view of components that may be included in anarticulated segment of an elongate articulated body, with the componentslaterally offset from their assembled position.

FIG. 13 schematically illustrates bending of a diagnosis or treatmentdelivery catheter into alignment with a target tissue by actuating aplurality of articulation sub-portions or segments of the catheter.

FIGS. 13A-13C schematically illustrate an exemplary multi-lumen cablestructure having an integrated stiffening balloon, a multi-lumen helicalcore structure, and a transition between a helical core and thinmulti-channel fluid transmission cable, respectively.

FIGS. 14A-14C illustrate components of an alternative embodiment havinga plurality of interleaved multi-lumen polymer helical cores interleavedwith a plurality of resilient coil structures having axially orientedsurfaces configured to radially restrain the balloons.

FIG. 15 is a perspective view of an alternative helical balloon corehaving a radially elongate cross-section to limit inflation fluid flowsand provide additional fluid channels and/or channel sizes.

FIG. 16 is a perspective view showing an exemplary introducersheath/input assembly having a flexible joystick for receiving movementcommands using relative movement between hands or fingers of a user.

FIGS. 17A and 17B are a perspective view and a cross-section ofcomponents of a catheter and fluid supply manifold system.

FIG. 18 is a simplified schematic of a modular manifold having a stackof valve plate assemblies through which a multi-lumen connector extendsso as to provide controlled fluid flow to and from balloons of an array.

FIGS. 19-22A schematically illustrate skeletons structures having framesor members with balloons mounted in opposition so as to axially extendwith inflation of one subset of the balloons, and to axially contractwith inflation of another subset of balloons.

FIGS. 22B and 22C are a schematic illustration of an exemplary axialexpansion/contraction skeleton with axial expansion and axialcontraction balloons; and a corresponding cross-section of a skeletonhaving an axial series of annular members or rings articulated by theaxial expansion and axial contraction balloons, respectively.

FIGS. 22D-22H are illustrations of elongate flexible articulatedstructures having annular skeletons with three opposed sets of balloons,and show how varying inflation of the balloons can be used to axiallycontract some portions of the frame and axially extend other portions tobend or elongate the frame and to control a pose or shape of the framein three dimensions.

FIGS. 23A-23J are illustrations of alternative elongate articulatedflexible structures having annular skeletons and two sets of opposedballoons, and show how a plurality of independently controllable axialsegments can be combined to allow control of the overall elongatestructure with 6 or more degrees of freedom.

FIGS. 24A-24G illustrate components of another alternative elongatearticulated flexible structure having axial expansion balloons andopposed axial contraction balloons, the structures here having helicalskeleton members and helical balloon assemblies.

FIGS. 25A-25F illustrate exemplary elongate articulated flexiblestructures having helical skeleton members and three helical balloonassemblies supported in opposition along the skeleton, and also show howselective inflation of subsets of the balloons can locally axiallyelongate and/or contract the skeleton to bend the structure laterallyand/or alter the overall length of the structure.

FIGS. 26A and 26B illustrate alternative articulated structures similarto those of FIG. 25, here with two balloon assemblies supported inopposition along the frames.

FIG. 27 illustrates alternative multi-lumen conduit or core structuresfor use in the balloon assemblies of FIGS. 24 and 25, showing a varietyof different numbers of channels that can be used with different numbersof articulated segments.

FIGS. 28A-28D illustrate an alternative interface for coupling a modularfluid manifold to a plurality of multi-lumen shafts so as to providecontrol over articulation of a catheter along a plurality of segments,each having a plurality of degrees of freedom, along with portions ofsome of the plate modules of the manifold, with the plate modules herehaving a receptacle member that helps couple the layers of the plates toposts of the interface.

FIGS. 29A-29E illustrate an alternative articulatable structure having asingle multi-lumen core with balloons extending eccentrically from thecore, along with details of the structure's components and assembly.

DETAILED DESCRIPTION OF THE INVENTION

The present invention generally provides fluid control devices, systems,and methods that are particularly useful for articulating catheters andother elongate flexible structures. In exemplary embodiments theinvention provides a modular manifold architecture that includesplate-mounted valves to facilitate fluid communication along a pluralityof fluid channels included in one or more multi-lumen shafts, often forarticulating actuators of a catheter. Preferred actuators includeballoons or other fluid-expandable bodies, and the modular manifoldassemblies are particularly well suited for independently controlling arelatively large number of fluid pressures and/or flows. The individualplate modules may include valves that control fluid supplied to acatheter or other device, and/or fluid exhausted from the catheter orother device. A receptacle extending across a stack of such modules canreceive a fluid flow interface having a large number of individual fluidcoupling ports, with the total volume of the modular valve assembly,including the paired receptacle and fluid flow interface of the deviceoften being quite small. In fact, the modular manifold will preferablybe small enough to hold in a single hand, even when a controller (suchas a digital processor), a pressurized fluid source (such as a canisterof cryogenic fluid), and an electrical power source (such as a battery)are included. When used to transmit liquids that will vaporize to a gasthat inflates a selected subset of microballoons within a microballoonarray, control over the small quantities of inflation liquids may directmicrofluidic quantities of inflation fluids. Microelectromechanicalsystem (MEMS) valves and sensors may find advantageous use in thesesystems; fortunately, suitable microfluidic and MEMS structures are nowcommercially available.

Embodiments provided herein may use balloon-like structures to effectarticulation of the elongate catheter or other body. The term“articulation balloon” may be used to refer to a component which expandson inflation with a fluid and is arranged so that on expansion theprimary effect is to cause articulation of the elongate body. Note thatthis use of such a structure is contrasted with a conventionalinterventional balloon whose primary effect on expansion is to causesubstantial radially outward expansion from the outer profile of theoverall device, for example to dilate or occlude or anchor in a vesselin which the device is located. Independently, articulated medialstructures described herein will often have an articulated distalportion, and an unarticulated proximal portion, which may significantlysimplify initial advancement of the structure into a patient usingstandard catheterization techniques.

The catheter bodies (and many of the other elongate flexible bodies thatbenefit from the inventions described herein) will often be describedherein as having or defining an axis, such that the axis extends alongthe elongate length of the body. As the bodies are flexible, the localorientation of this axis may vary along the length of the body, andwhile the axis will often be a central axis defined at or near a centerof a cross-section of the body, eccentric axes near an outer surface ofthe body might also be used. It should be understood, for example, thatan elongate structure that extends “along an axis” may have its longestdimension extending in an orientation that has a significant axialcomponent, but the length of that structure need not be preciselyparallel to the axis. Similarly, an elongate structure that extends“primarily along the axis” and the like will generally have a lengththat extends along an orientation that has a greater axial componentthan components in other orientations orthogonal to the axis. Otherorientations may be defined relative to the axis of the body, includingorientations that are transverse to the axis (which will encompassorientation that generally extend across the axis, but need not beorthogonal to the axis), orientations that are lateral to the axis(which will encompass orientations that have a significant radialcomponent relative to the axis), orientations that are circumferentialrelative to the axis (which will encompass orientations that extendaround the axis), and the like. The orientations of surfaces may bedescribed herein by reference to the normal of the surface extendingaway from the structure underlying the surface. As an example, in asimple, solid cylindrical body that has an axis that extends from aproximal end of the body to the distal end of the body, the distal-mostend of the body may be described as being distally oriented, theproximal end may be described as being proximally oriented, and thesurface between the proximal and distal ends may be described as beingradially oriented. As another example, an elongate helical structureextending axially around the above cylindrical body, with the helicalstructure comprising a wire with a square cross section wrapped aroundthe cylinder at a 20 degree angle, might be described herein as havingtwo opposed axial surfaces (with one being primarily proximallyoriented, one being primarily distally oriented). The outermost surfaceof that wire might be described as being oriented exactly radiallyoutwardly, while the opposed inner surface of the wire might bedescribed as being oriented radially inwardly, and so forth.

Referring first to FIG. 1, a first exemplary catheter system 1 andmethod for its use are shown. A physician or other system user Uinteracts with catheter system 1 so as to perform a therapeutic and/ordiagnostic procedure on a patient P, with at least a portion of theprocedure being performed by advancing a catheter 3 into a body lumenand aligning an end portion of the catheter with a target tissue of thepatient. More specifically, a distal end of catheter 3 is inserted intothe patient through an access site A, and is advanced through one of thelumen systems of the body (typically the vasculature network) while userU guides the catheter with reference to images of the catheter and thetissues of the body obtained by a remote imaging system.

Exemplary catheter system 1 will often be introduced into patient Pthrough one of the major blood vessels of the leg, arm, neck, or thelike. A variety of known vascular access techniques may also be used, orthe system may alternatively be inserted through a body orifice orotherwise enter into any of a number of alternative body lumens. Theimaging system will generally include an image capture system 7 foracquiring the remote image data and a display D for presenting images ofthe internal tissues and adjacent catheter system components. Suitableimaging modalities may include fluoroscopy, computed tomography,magnetic resonance imaging, ultrasonography, combinations of two or moreof these, or others.

Catheter 3 may be used by user U in different modes during a singleprocedure, including two or more of a manual manipulation mode, anautomated and powered shape-changing mode, and a combination mode inwhich the user manually moves the proximal end while a computerarticulates the distal portion. More specifically, at least a portion ofthe distal advancement of catheter 3 within the patient may be performedin a manual mode, with system user U manually manipulating the exposedproximal portion of the catheter relative to the patient using hands H1,H2. Catheter 3 may, for example, be manually advanced over a guidewire,using either over-the-wire or rapid exchange techniques. Catheter 3 mayalso be self-guiding during manual advancement (so that for at least aportion of the advancement of catheter 3, a distal tip of the cathetermay guide manual distal advancement). Automated lateral deflection of adistal portion of the catheter may impose a desired distal steering bendprior to a manual movement, such as near a vessel bifurcation, followedby manual movement through the bifurcation. In addition to such manualmovement modes, catheter system 1 may also have a 3-D automated movementmode using computer controlled articulation of at least a portion of thelength of catheter 3 disposed within the body of the patient to changethe shape of the catheter portion, often to advance or position thedistal end of the catheter. Movement of the distal end of the catheterwithin the body will often be provided per real-time or near real-timemovement commands input by user U, with the portion of the catheter thatchanges shape optionally being entirely within the patient so that themovement of the distal portion of the catheter is provided withoutmovement of a shaft or cable extending through the access site. Stillfurther modes of operation of system 1 may also be implemented,including concurrent manual manipulation with automated articulation,for example, with user U manually advancing the proximal shaft throughaccess site A while computer-controlled lateral deflections and/orchanges in stiffness over a distal portion of the catheter help thedistal end follow a desired path or reduce resistance to the axialmovement.

Referring next to FIG. 1-1 components which may be included in or usedwith catheter system 1 or catheter 3 (described above) can be more fullyunderstood with reference to an alternative catheter system 10 and itscatheter 12. Catheter 12 generally includes an elongate flexiblecatheter body and is detachably coupled to a handle 14, preferably by aquick-disconnect coupler 16. Catheter body 12 has an axis 30, and aninput 18 of handle 14 can be moved by a user so as to locally alter theaxial bending characteristics along catheter body 12, often for variablyarticulating an actuated portion 20 of the catheter body. Catheter body12 will often have a working lumen 26 into or through which atherapeutic and/or diagnostic tool may be advanced from a proximal port28 of handle 14. Alternative embodiments may lack a working lumen, mayhave one or more therapeutic or diagnostic tools incorporated into thecatheter body near or along actuated portion 20, may have a sufficientlysmall outer profile to facilitate use of the body as a guidewire, maycarry a tool or implant near actuated portion 20 or near distal end 26,or the like. In particular embodiments, catheter body 12 may support atherapeutic or diagnostic tool 8 proximal of, along the length of,and/or distal of actuated portion 20. Alternatively, a separate elongateflexible catheter body may be guided distally to a target site oncecatheter body 20 has been advanced (with the elongate body for such usesoften taking the form and use of a guidewire or guide catheter).

The particular tool or tools included in, advanceable over, and/orintroducible through the working lumen of catheter body 20 may includeany of a wide range of therapeutic and/or treatment structures. Examplesinclude cardiovascular therapy and diagnosis tools (such as angioplastyballoons, stent deployment balloons or other devices, atherectomydevices, tools for detecting, measuring, and/or characterizing plaque orother occlusions, tools for imaging or other evaluation of, and/ortreatment of, the coronary or peripheral arteries, structural hearttools (including prostheses or other tools for valve procedures, foraltering the morphology of the heart tissues, chambers, and appendages,and the like), tools for electrophysiology mapping or ablation tools,and the like); stimulation electrodes or electrode implantation tools(such as leads, lead implant devices, and lead deployment systems,leadless pacemakers and associated deployments systems, and the like);neurovascular therapy tools (including for accessing, diagnosis and/ortreatment of hemorrhagic or ischemic strokes and other conditions, andthe like); gastrointestinal and/or reproductive procedure tools (such ascolonoscopic diagnoses and intervention tools, transurethral proceduretools, transesophageal procedure tools, endoscopic bariatric proceduretools, etc.); hysteroscopic and/or falloposcopic procedure tools, andthe like; pulmonary procedure tools for therapies involving the airwaysand/or vasculature of the lungs; tools for diagnosis and/or treatment ofthe sinus, throat, mouth, or other cavities, and a wide variety of otherendoluminal therapies and diagnoses structures. Such tools may make useof known surface or tissue volume imaging technologies (includingimaging technologies such as 2-D or 3-D cameras or other imagingtechnologies; optical coherence tomography technologies; ultrasoundtechnologies such as intravascular ultrasound, transesophogealultrasound, intracardiac ultrasound, Doppler ultrasound, or the like;magnetic resonance imaging technologies; and the like), tissue or othermaterial removal, incising, and/or penetrating technologies (such arotational or axial atherectomy technologies; morcellation technologies;biopsy technologies; deployable needle or microneedle technologies;thrombus capture technologies; snares; and the like), tissue dilationtechnologies (such as compliant or non-compliant balloons, plasticallyor resiliently expandable stents, reversibly expandable coils, braids orother scaffolds, and the like), tissue remodeling and/or energy deliverytechnologies (such as electrosurgical ablation technologies, RFelectrodes, microwave antennae, cautery surfaces, cryosurgicaltechnologies, laser energy transmitting surfaces, and the like), localagent delivery technologies (such as drug eluting stents, balloons,implants, or other bodies; contrast agent or drug injection ports;endoluminal repaving structures; and the like), implant and prosthesisdeploying technologies, anastomosis technologies and technologies forapplying clips or sutures, tissue grasping and manipulationtechnologies; and/or the like. In some embodiments, the outer surface ofthe articulation structure may be used to manipulate tissues directly.Non-medical embodiments may similarly have a wide range of tools orsurfaces for industrial, assembly, imaging, manipulation, and otheruses.

Addressing catheter body 12 of system 10 (and particularly articulationcapabilities of actuated portion 20) in more detail, the catheter bodygenerally has a proximal end 22 and a distal end 24 with axis 30extending between the two. As can be understood with reference to FIG.2, catheter body 12 may have a short actuated portion 20 of about 3diameters or less, but will often have an elongate actuated portion 20extending intermittently or continuously over several diameters of thecatheter body (generally over more than 3 diameters, often over morethan 10 diameters, in many cases over more than 20 diameters, and insome embodiments over more than 40 diameters). A total length ofcatheter body 12 (or other flexible articulated bodies employing theactuation components described herein) may be from 5 to 500 cm, moretypically being from 15 to 260 cm, with the actuated portion optionallyhaving a length of from 1 to 150 cm (more typically being 2 to 20 cm)and an outer diameter of from 0.65 mm to 5 cm (more typically being from1 mm to 2 cm). Outer diameters of guidewire embodiments of the flexiblebodies may be as small as 0.012″ though many embodiments may be morethan 2 Fr, with catheter and other medical embodiments optionally havingouter diameters as large as 34 French or more, and with industrialrobotic embodiments optionally having diameters of up to 1″ or more.Exemplary catheter embodiments for structural heart therapies (such astrans-catheter aortic or mitral valve repair or implantation, leftatrial appendage closure, and the like) may have actuated portions withlengths of from 3 to 30 cm, more typically being from 5 to 25 cm, andmay have outer profiles of from 10 to 30 Fr, typically being from 12 to18 Fr, and ideally being from 13 to 16 Fr. Electrophysilogy therapycatheters (including those having electrodes for sensing heart cyclesand/or electrodes for ablating selected tissues of the heart) may havesizes of from about 5 to about 12 Fr, and articulated lengths of fromabout 3 to about 30 cm. A range of other sizes might also be implementedfor these or other applications.

Referring now to FIGS. 1A, 1B, and 1C, system 10 may be configured toarticulate actuated portion 20. Articulation will often allow movementcontinuously throughout a range of motion, though some embodiments mayprovide articulation in-part or in-full by selecting from among aplurality of discrete articulation states. Catheters having opposedaxial extension and contraction actuators are described herein that maybe particularly beneficial for providing continuous controlled andreversible movement, and can also be used to modulate the stiffness of aflexible structure. These continuous and discrete systems share manycomponents (and some systems might employ a combination of bothapproaches). First addressing the use of a discrete state system, FIG.1A, system 10 can, for example, increase an axial length of actuatedportion 20 by one or more incremental changes in length ΔL. An exemplarystructure for implementation of a total selectable increase in length ΔLcan combine a plurality of incremental increases in length ΔL=ΔL₁+ΔL₂+ .. . ), as can be understood with reference to FIG. 4D. As shown in FIGS.1B and 1C, system 10 may also deflect distal end 24 to a first bentstate having a first bend angle 31 between unarticulated axis 30 and anarticulated axis 30′ (as shown schematically in FIG. 1B), or to a secondbent state having a total bend angle 33 (between articulated axis 30 andarticulated axis 30″), with this second bend angle being greater thanthe first bend angle (as shown schematically in FIG. 1C). An exemplarystructure for combining multiple discrete bend angle increments to forma total bend angle 33 can be understood with reference to FIG. 4C.Regardless, the additional total cumulative bend angle 33 may optionallybe implemented by imposing the first bend 31 (of FIG. 1B) as a firstincrement along with one or more additional bend angle increments 35.The incremental changes to actuated portion 20 may be provided by fullyinflating and/or deflating actuation balloons of the catheter system.Bend capabilities may be limited to a single lateral orientation, butwill more typically be available in different lateral orientations, mosttypically in any of 3 or 4 orientations (for example, using balloonspositioned along two pairs of opposed lateral axes, sometimes referredto as the +X, −X, +Y and −Y orientations), and by combining differentbend orientations, in intermediate orientations as well. Continuouspositioning may be implemented using similar articulation structures bypartially inflating or deflating balloons or groups of balloons.

System 10 may also be configured to provide catheter 12 with any of aplurality of discrete alternative total axial lengths. As with the bendcapabilities, such length actuation may also be implemented by inflatingballoons of a balloon array structure. To provide articulation with thesimple balloon array structures described herein, each actuation may beimplemented as a combination of discrete, predetermined actuationincrements (optionally together with one or more partial or modulatedactuation) but may more often be provided using modulated or partialinflation of some, most, or all of the balloons.

Referring now to FIGS. 1-1 and 2, embodiments of articulation system 10will move the distal end 24 of catheter 12 toward a desired positionand/or orientation in a workspace relative to a base portion 21, withthe base portion often being adjacent to and proximal of actuatedportion 20. Note that such articulation may be relatively (or evencompletely) independent of any bending of catheter body 12 proximal ofbase portion 21. The location and orientation of proximal base 21(relative to handle 14 or to another convenient fixed or movablereference frame) may be identified, for example, by including knowncatheter position and/or orientation identification systems in system10, by including radiopaque or other high-contrast markers andassociated imaging and position and/or orientation identifying imageprocessing software in system 10, by including a flexible body statesensor system along the proximal portion of catheter body 12, byforegoing any flexible length of catheter body 12 between proximalhandle 14 and actuated portion 20, or the like. A variety of differentdegrees of freedom may be provided by actuated portion 20. Exemplaryembodiments of articulation system 10 may allow, for example, distal end24 to be moved with 2 degrees of freedom, 3 degrees of freedom, 4degrees of freedom, 5 degrees of freedom, or 6 degrees of freedomrelative to base portion 21. The number of kinematic degrees of freedomof articulated portion 20 may be much higher in some embodiments,particularly when a number of different alternative subsets of theballoon array could potentially be in different inflation states to givethe same resulting catheter tip and/or tool position and orientation.

Note that the elongate catheter body 12 along and beyond actuatedportion 20 may (and often should) remain flexible before, during, andafter articulation, so as to avoid inadvertently applying lateral and/oraxial forces to surrounding tissues that are beyond a safe threshold.Nonetheless, embodiments of the systems described herein may locally andcontrollable increase a stiffness of one or more axial portions ofcatheter body 12, along actuated portion 20, proximal of actuatedportion 20, and/or distal of actuated portion 20. Such selectivestiffening of the catheter body may be implemented with or withoutactive articulation capabilities, may extend along one or more axialportion of catheter body 12, and may alter which portions are stiffenedand which are more flexible in response to commands from the user,sensor input (optionally indicating axial movement of the catheter), orthe like.

As shown in FIG. 2, actuated portion 20 may comprise an axial series of2 or more (and preferably at least 3) actuatable sub-portions orsegments 20′, 20″, 20′″, with the segments optionally being adjacent toeach other, or alternatively separated by relatively short (less than 10diameters) and/or relatively stiff intermediate portions of catheter 12.Each sub-portion or segment may have an associated actuation array, withthe arrays working together to provide the desired overall cathetershape and degrees of freedom to the tip or tool. At least 2 of thesub-portions may employ similar articulation components (such as similarballoon arrays, similar structural backbone portions, similar valvesystems, and/or similar software). Commonality may include the use ofcorresponding actuation balloon arrays, but optionally with thecharacteristics of the individual actuation balloons of the differentarrays and the spacing between the locations of the arrays varying forany distal tapering of the catheter body. There may be advantages to theuse of differentiated articulation components, for example, withproximal and distal sub portions, 20′, 20′″ having similar structuresthat are configured to allow selective lateral bending with at least twodegrees of freedom, and intermediate portion 20″ being configured toallow variable axial elongation. In many embodiments, however, at leasttwo (and preferably all) segments are substantially continuous and sharecommon components and geometries, with the different segments havingseparate fluid channels and being separately articulatable but eachoptionally providing similar movement capabilities.

For those elongate flexible articulated structures described herein thatinclude a plurality of axial segments, the systems will often determineand implement each commanded articulation of a particular segment as asingle consistent articulation toward a desired segment shape state thatis distributed along that segment. In some exemplary embodiments, thenominal or resting segment shape state may be constrained to a 3 DOFspace (such as by continuous combinations of two transverse lateralbending orientations and an axial (elongation) orientation in an X-Y-Zwork space). In some of the exemplary embodiments described herein(including at least some of the helical extension/contractionembodiments), lateral bends along a segment may be at leastapproximately planar when the segment is in or near a design axiallength configuration (such as at or near the middle of the axial or Zrange of motion), but may exhibit a slight but increasing off-planetwisting curvature as the segment moves away from that designconfiguration (such as near the proximal and/or distal ends of the axialrange of motion). The off-plane bending may be repeatably accounted forkinematically by determining the changes in lateral orientation ofeccentric balloons resulting from winding and unwinding of helicalstructures supporting those balloons when the helical structuresincrease and decrease in axial length. For example, a segment may becommanded (as part of an overall desired pose or movement) to bend in a−Y orientation with a 20 degree bend angle. If the bend is to occur at adesign axial length (such as at the middle of the axial range ofmotion), and assuming balloons (or opposed balloon pairs) at 4 axialbend locations can be used to provide the commanded bend, the balloons(or balloon pairs) may each be inflated or deflated to bend the segmentby about 5 degrees (thereby providing a total bend of 5*4 or 20 degrees)in the −Y orientation. If the same bend is to be combined with axiallengthening of the segment to the end of its axial range of motion, theprocessor may determine that the segment may would exhibit some twist(say 2 degrees) so that there would be a slight +X component to thecommanded bend, so that the processor may compensate for the twist bycommanding a corresponding −X bend component, or by otherwisecompensating in the command for another segment of the flexible body. Inlight of the above, it should be understood that in some embodiments theballoons aligned along a lateral bending orientation may not beprecisely aligned parallel to the axis of the segment, as a balloon of asubset that is aligned along a lateral bending orientation may beslightly offset circumferentially (generally less than 20 degrees, moretypically less than 10 or even 5 degrees, and ideally less than 2½degrees) from the adjacent balloon(s) of that subset when the segment isin at least some axial configurations. Nonetheless, the balloons alignedalong a lateral bending orientation may cooperate to bend the axis ofthe segment in a primarily common lateral orientation.

Referring to FIGS. 3 and 5, catheter body 12 of system 10 includes anactuation array structure 32 mounted to a structural skeleton (here inthe form of a helical coil 34). Exemplary balloon array 32 includesfluid expandable structures or balloons 36 distributed at balloonlocations along a flexible substrate 38 so as to define an M×N array, inwhich M is an integer number of balloons distributed about acircumference 50 of catheter 12 at a given location along axis 30, and Nrepresents an integer number of axial locations along catheter 12 havingactuation balloons. Circumferential and axial spacing of the arrayelement locations will generally be known, and will preferably beregular. This first exemplary actuation array includes a 4×4 array for atotal of 16 balloons; alternative arrays may be from 1×2 arrays for atotal of 2 balloons to 8×200 arrays for a total of 1600 balloons (orbeyond), more typically having from 3×3 to 6×20 arrays. While balloonarrays of 1×N may be provided (particularly on systems that rely onrotation of the catheter body to orient a bend), M will more typicallybe 2 or more, more often being from 3 to 8, and preferably being 3 or 4.Similarly, while balloon arrays of M×1 may be provided to allowimposition of a single bend increment at a particular location in any ofa number of different desired lateral orientations, array 32 will moretypically have an N of from 2 to 200, often being from 3 to 20 or 3 to100. In contraction/expansion embodiments described below, multiplearrays may be provided with similar M×N arrays mounted in opposition.Not all array locations need have inflatable balloons, and the balloonsmay be arranged in more complex arrangements, such as with alternatingcircumferential numbers of balloons along the axis, or with varying oralternating separation between balloons along the axial length of thearray.

The balloons of a particular segment or that are mounted to a commonsubstrate may be described as forming an array, with the actuationballoon array structure optionally being used as a sub-array in amulti-segment or opposed articulation system. The combined sub-arraystogether may form an array of the overall device, which may also bedescribed simply as an array or optionally an overall or combined array.Exemplary balloon arrays along a segment or sub-portion of articulatedportion 20 include 1×8, 1×12, and 1×16 arrays for bending in a singledirection (optionally with 2, 3, 4, or even all of the balloons of thesegment in fluid communication with a single common inflation lumen soas to be inflated together) and 4×4, 4×8, and 4×12 arrays for X-Ybending (with axially aligned groups of 2-12 balloons coupled with 4 ormore common lumens for articulation in the +X, −X, +Y, and −Yorientations). Exemplary arrays for each segment having the opposedextension/retraction continuous articulation structures described hereinmay be in the form of a 3×2N, 3×3N, 4×2N, or 4×3N balloons arrays, forexample, 3×2, 3×4, 3×6, 3×8, 3×10, 3×12, 3×14, and 3×16 arrays with 6 to48 balloons, with the 3 lateral balloon orientations separated by 120degrees about the catheter axis. Extension balloons will often beaxially interspersed with contraction balloons along each lateralorientation, with separate 3×N arrays being combined together in a 3×2Nextension/contraction array for the segment, while two extensionballoons may be positioned axially between each contraction balloon for3×3N arrangements. The contraction balloons may align axially and/or bein plane with the extension balloons they oppose, though it may beadvantageous in some embodiments to arrange opposed balloons offset froma planer arrangement, so that (for example) two balloons of one typebalance one balloon of the other, or vice versa. The extension balloonsalong each orientation of the segment may share a common inflation fluidsupply lumen while the contraction balloons of the segment for eachorientation similarly share a common lumen (using 6 fluid supply lumensper segment for both 3×2N and 3 ×3N arrays). An extension/contractioncatheter may have from 1 to 8 such segments along the articulatedportion, more typically from 1 to 5 segments, and preferably being 2 to4 segments. Some embodiments of extension/contraction systems may havean additional load-behaviour balloon array system extending along one,some, or all of the segments, with the array and fluid control systemconfigured to improve the predictability of the associated segment(s)under various loads. Exemplary load-behavior balloon arrays may take theform of a 4×N array (N optionally being the same as the N extensionarray for the segment, and 4 (or another even number) lateral balloonorientations being even when the same segment has a 3×N actuationarray). Other medical and non-medical elongate flexible articulatedstructures may have similar or more complex balloon articulation arrays.

As can be seen in FIGS. 3, 4A, 4B, and 4C, the skeleton will often(though not always) include an axial series of loops 42. When the loopsare included in a helical coil 34, the coil may optionally be biased soas to urge adjacent loops 42 of the coil 34 toward each other. Suchaxially compressive biasing may help urge fluid out and deflate theballoons, and may by applied by other structures (inner and/or outersheath(s), pull wires, etc.) with or without helical compression. Axialengagement between adjacent loops (directly, or with balloon walls orother material of the array between loops) can also allow compressiveaxial forces to be transmitted relatively rigidly when the balloons arenot inflated. When a particular balloon is fully inflated, axialcompression may be transmitted between adjacent loops by the fullyinflated balloon wall material and by the fluid within the balloons.Where the balloon walls are non-compliant, the inflated balloons maytransfer these forces relatively rigidly, though with some flexing ofthe balloon wall material adjacent the balloon/skeleton interface. Rigidor semi-rigid interface structures which distribute axial loads across abroader balloon interface region may limit such flexing. Axial tensionforces (including those associated with axial bending) may be resistedby the biasing of the skeleton (and/or by other axial compressivestructures). Alternative looped skeleton structures may be formed, forexample, by cutting hypotube with an axial series of lateral incisionsacross a portion of the cross-section from one or more lateralorientations, braided metal or polymer elements, or the like. Non-loopedskeletons may be formed using a number of alternative known rigid orflexible robotic linkage architectures, including with structures basedon known soft robot structures. Suitable materials for coil 34 or otherskeleton structures may comprise metals such as stainless steel, springsteel, superelastic or shape-memory alloys such as Nitinol™ alloys,polymers, fiber-reinforced polymers, high-density or ultrahigh-densitypolymers, or the like.

When loops are included in the skeleton, actuation array 32 can bemounted to the skeleton with at least some of the balloons 36 positionedbetween two adjacent associated loops 42, such as between the loops ofcoil 34. Referring now to FIG. 4C, an exemplary deflated balloon 36 i islocated between a proximally adjacent loop 42 i and a distally adjacentloop 42 ii, with a first surface region of the balloon engaging adistally oriented surface of proximal loop 34 i, and a second surfaceregion of the balloon engaging a proximally oriented surface of distalloop 42 ii. The walls of deflated balloon 36 i have some thickness, andthe proximal and distal surfaces of adjacent loops 42 i and 42 iimaintain a non-zero axial deflated offset 41 between the loops. Axialcompression forces can be transferred from the loops through the solidballoon walls. Alternative skeletal structures may allow the loops toengage directly against each other so as to have a deflated offset ofzero and directly transmit axial compressive force, for example byincluding balloon receptacles or one or more axial protrusions extendingfrom one or both loops circumferentially or radially beyond the balloonand any adjacent substrate structure. Regardless, full inflation of theballoon will typically increase the separation between the adjacentloops to a larger full inflation offset 41′. The simplified lateralcross-sections of FIGS. 4B, 4C, and 4D schematically show a directinterface engagement between a uniform thickness thin-walled balloon anda round helical coil loop. Such an interface may result in relativelylimited area of the balloon wall engaging the coil and associateddeformation under axial loading. Alternative balloon-engaging surfaceshapes along the coils (often including locally increased convex radii,locally flattened surfaces, and/or local concave balloon receptacles)and/or along the coil-engaging surfaces of the balloon (such as bylocally thickening the balloon wall to spread the engagement area),and/or providing load-spreading bodies between the balloons and thecoils may add axial stiffness. A variety of other modifications to theballoons and balloon/coil interfaces may also be beneficial, includingadhesive bonding of the balloons to the adjacent coils, including foldsor material so as to inhibit balloon migration, and the like.

Inflation of a balloon can alter the geometry along catheter body 12,for example, by increasing separation between loops of a helical coil soas to bend axis 30 of catheter 12. As can be understood with referenceto FIGS. 1B, 1C and 4-4C, selectively inflating an eccentric subset ofthe balloons can variably alter lateral deflection of the catheter axis.As can be understood with reference to FIGS. 1A, 4, and 4D, inflation ofall (or an axisymmetric subset) of the balloons may increase an axiallength of the catheter structure. Inflating subsets of the balloons thathave a combination of differing lateral orientations and axial positionscan provide a broad range of potential locations and orientations of thecatheter distal tip 26, and/or of one or more other locations along thecatheter body (such as where a tool is mounted).

Some or all of the material of substrate 38 included in actuation array32 will often be relatively inelastic. It may, however, be desirable toallow the skeleton and overall catheter to flex and/or elongate axiallywith inflation of the balloons or under environmental forces. Hence,array 32 may have cutouts 56 so as to allow the balloon array to moveaxially with the skeleton during bending and elongation. The arraystructure could alternatively (or in addition) be configured for sucharticulation by having a serpentine configuration or a helical coiledconfiguration. Balloons 36 of array 32 may include non-compliant balloonwall materials, with the balloon wall materials optionally being formedintegrally from material of the substrate or separately. Note thatelastic layers or other structures may be included in the substrate foruse in valves and the like, and that some alternative balloons mayinclude elastic and/or semi-compliant materials.

Referring to FIGS. 3, 4A, and 5, substrate 38 of array 32 is laterallyflexible so that the array can be rolled or otherwise assume acylindrical configuration when in use. The cylindrical array may becoaxially mounted to (such as being inserted into or radially outwardlysurrounding) the helical coil 34 or other structural backbone of thecatheter. The cylindrical configuration of the array will generally havea diameter that is equal to or less than an outer diameter of thecatheter. The opposed lateral edges of substrate 38 may be separated bya gap as shown, may contact each other, or may overlap. Contacting oroverlapping edges may be affixed together (optionally so as to help sealthe catheter against radial fluid flow) or may accommodate relativemotion (so as to facilitate axial flexing). In some embodiments, lateralrolling or flexing of the substrate to form the cylindricalconfiguration may be uniform (so as to provide a continuous lateralcurve along the major surfaces), while in other embodiments intermittentaxial bend regions of the substrate may be separated by axially elongaterelatively flat regions of the substrate so that a cylindrical shape isapproximated by a prism-like arrangement (optionally so as to limitbending of the substrate along balloons, valves, or other arraycomponents).

It will often (though not always) be advantageous to form and/orassemble one or more components of the array structure in a flat,substantially planar configuration (and optionally in a linearconfiguration as described below). This may facilitate, for example,partial or final formation of balloons 36 on substrate 38, oralternatively, attachment of pre-formed balloons to the substrate. Theflat configuration of the substrate may also facilitate the use of knownextrusion or microfluidic channel fabrication techniques to providefluid communication channels 52 so as to selectively couple the balloonswith a fluid inflation fluid source or reservoir 54, and the like. Stillfurther advantages of the flat configuration of the substrate mayinclude the use of electrical circuit printing techniques to fabricateelectrical traces and other circuit components, automated 3-D printingtechniques (including additive and/or removal techniques) for formingvalves, balloons, channels, or other fluid components that will besupported by substrate 38, and the like. When the substrate is in arolled, tubular, or flat planar configuration, the substrate willtypically have a first major surface 62 adjacent balloons 36, and asecond major surface 64 opposite the first major surface (with firstmajor surface 62 optionally being a radially inner or outer surface andsecond major surface 64 being a radially outer or inner surface,respectively, in the cylindrical configuration). To facilitate flexingsubstrate 38 and array 32 into the rolled configuration, relief cuts orchannels may be formed extending into the substrate from the firstand/or second major surfaces, or living hinge regions may otherwise beprovided between relatively more rigid portions of the substrate. Tofurther avoid deformation of the substrate adjacent any valves or othersensitive structures, local stiffening reinforcement material may beadded, and/or relief cuts or apertures may be formed partiallysurrounding the valves. In some embodiments, at least a portion of thearray components may be formed or assembled with the substrate at leastpartially in a cylindrical configuration, such as by bonding layers ofthe substrate together while the substrate is at least locally curved,forming at least one layer of the substrate as a tube, selectivelyforming cuts in the substrate (optionally with a femtosecond,picosecond, or other laser) to form fluid, circuit, or other componentsor allow for axial flexing and elongation (analogous to cutting a stentto allow for axial flexing and radial expansion) and/or to form at leastsome of the channels, and bonding the layers together after cutting.

As can be understood with reference to FIGS. 5-5C, substrate 38 of array32 may include one or more layers 70, 72, 74 . . . of flexible substratematerial. The substrate layers may comprise known flexible and/or rigidmicrofluidic substrate materials, such as polydimethylsiloxane (PDMS),polyimide (PI), polyethylene (PE) and other polyolefins, polystyrene(PS), polyethylene terephthalate (PET), polypropylene (PP),polycarbonate (PC), nanocomposite polymer materials, glass, silicon,cyclic olefin copolymer (COC), polymethyl methacrylate (PMMA),polyetheretherketone (PEEK), polyester, polyurethane (PU), and/or thelike. These and still further known materials may be included in othercomponents of actuation array 32, including known polymers for use inballoons (which will often include PET, PI, PE, polyether block amide(PEBA) polymers such as PEBAX™ polymers, nylons, urethanes, polyvinylchloride (PVC), thermoplastics, and/or the like for non-compliantballoons; or silicone, polyurethane, semi-elastic nylons or otherpolymers, latex, and/or the like for compliant or semi-compliantballoons). Additional polymers than may be included in the substrateassembly may include valve actuation elements (optionally includingshape memory alloy structures or foils; phase-change actuator materialssuch as paraffin or other wax, electrical field sensitive hydrogels,bimetallic actuators, piezoelectric structures, dielectric elastomeractuator (DEA) materials, or the like). Hence, while some embodimentsmay employ homogenous materials for actuation array 32, many arrays andsubstrate may instead be heterogeneous.

Fortunately, techniques for forming and assembling the components foractuation array 32 may be derived from a number of recent (andrelatively widely-reported) technologies. Suitable techniques forfabricating channels in substrate layer materials may include lasermicromachining (optionally using femtosecond or picosecond lasers),photolithography techniques such as dry resist technologies, embossing(including hot roller embossing), casting or molding, xerographictechnologies, microthermoforming, stereolithography, 3-D printing,and/or the like. Suitable 3-D printing technologies that may be used toform circuitry, valves, sensors, and the like may includestereolithography, digital light processing, laser sintering or melting,fused deposition modeling, inkjet printing, selective depositionlamination, electron beam melting, or the like. Assembly of thecomponents of actuation array 32 may make use of laser, thermal, and/oradhesive bonding between layers and other components, though laser,ultrasound, or other welding techniques; microfasteners, or the like mayalso be used. Electrical element fabrication of conductive traces,actuation, signal processor, and/or sensor components carried bysubstrate 38 may, for example, use ink-jet or photolithographytechniques, 3-D printing, chemical vapor deposition (CVD) and/or morespecific variants such as initiated chemical vapor deposition (iCVD),robotic microassembly techniques, or the like, with the electricaltraces and other components often comprising inks and other materialscontaining metals (such as silver, copper, or gold) carbon, or otherconductors. Many suitable fabrication and assembly techniques have beendeveloped during development of microfluidic lab-on-a-chip orlab-on-a-foil applications. Techniques for fabricating medical balloonsare well developed, and may optionally be modified to take advantage ofknown high-volume production techniques (optionally including thosedeveloped for fabricating bubble wrap, for corrugating extruded tubing,and the like). Note that while some embodiments of the actuation arraystructures described herein may employ fluid channels sufficiently smallfor accurately handling of picoliter or nanoliter fluid quantities,other embodiments will include channels and balloons or otherfluid-expandable bodies that utilize much larger flows so as to providedesirable actuation response times. Balloons having at least partiallyflexible balloon walls may provide particular advantages for the systemsdescribed herein, but alternative rigid fluid expandable bodies such asthose employing pistons or other positive displacement expansionstructures may also find use in some embodiments.

The structures of balloons 36 as included in actuation array 32 may beformed of material integral with other components of the array, or maybe formed separately and attached to the array. For example, as shown inFIGS. 5B and 5C, balloons 36 may be formed from or attached to a firstsheet 74 of substrate material that can be bonded or otherwise affixedto another substrate layer 72 or layers. The material of the balloonlayer 74 may optionally cover portions of the channels directly, or maybe aligned with apertures 78 that open through an intermediate substratelayer surface between the channels and the balloons. Apertures 78 mayallow fluid communication between each balloon and at least oneassociated channel 52. Alternative methods for fabricating individualballoons are well known, and the formed balloons may be affixed to thesubstrate 38 by adhesive bonding. Balloon shapes may comprise relativelysimple cylinders or may be somewhat tailored to taper to follow anexpanded offset between loops of a coil, to curve with the cylindricalsubstrate and/or to engage interface surfaces of the skeleton over abroader surface area and thereby distribute actuation and environmentalloads. Effective diameters of the balloons in the array may range fromabout 0.003 mm to as much as about 2 cm (or more), more typically beingin a range from about 0.3 mm to about 2 mm or 5 mm, with the balloonlengths often being from about 2 to about 15 times the diameter. Typicalballoon wall thicknesses may range from about 0.0002 mm to about 0.004mm (with some balloon wall thicknesses being between 0.0002 mm and 0.020mm), and full inflation pressures in the balloons may be from about 0.2to about 40 atm, more typically being in a range from about 0.4 to about30 atm, and in some embodiments being in a range from about 10 to about30 atm, with high-pressure embodiments operating at pressures in a rangeas high as 20-45 atm and optionally having burst pressures of over 50atm.

Referring now to FIG. 5, balloons 36 will generally be inflated using afluid supply system that includes a fluid source 54 (shown here as apressurized single-use cartridge) and one or more valves 90. At leastsome of the valves 90 may be incorporated into the balloon arraysubstrate, with the valves optionally being actuated using circuitryprinted on one or more layers of substrate 38. With or withoutsubstrate-mounted valves that can be used within a patient body, atleast some of the valves may be mounted to housing 14, or otherwisecoupled to the proximal end of catheter 12. Valves 90 will preferably becoupled to channels 52 so as to allow the fluid system to selectivelyinflate any of a plurality of alternative individual balloons or subsetsof balloons 36 included in actuation array 32, under the direction of aprocessor 60. Hence, processor 60 will often be coupled to valves 90 viaconductors, the conductors here optionally including flex circuit traceson substrate 38.

Referring still to FIG. 5, fluid source 54 may optionally comprise aseparate fluid reservoir and a pump for pressurizing fluid from thereservoir, but will often include a simple tank or cartridge containinga pressurized fluid, the fluid optionally being a gas or a gas-liquidmixture. The cartridge will often maintain the fluid at a supplypressure at or above a full inflation pressure range of balloons 36,with the cartridge optionally being gently heated by a resistive heateror the like (not shown) in housing 14 so as to maintain the supplypressure within a desired range in the cartridge during use. Supplypressures will typically exceed balloon inflation pressures sufficientlyto provide balloon inflation times within a target threshold given thepressure loss through channels 52 and valves 90, with typical supplypressures being between 10 and 210 atm, and more typically being between20 and 60 atm. Suitable fluids may include known medical pressurizedgases such as carbon dioxide, nitrogen, oxygen, nitrous oxide, air,known industrial and cryogenic gasses such as helium and/or other inertor noble gasses, refrigerant gases including fluorocarbons, and thelike. Note that the pressurized fluid in the canister can be directedvia channels 52 into balloons 36 for inflation, or the fluid from thecanister (often at least partially a gas) may alternatively be used topressurize a fluid reservoir (often containing or comprising a benignbiocompatible liquid such as water or saline) so that the ballooninflation fluid is different than that contained in the cartridge. Wherea pressurized liquid or gas/liquid mixture flows distally along thecatheter body, enthalpy of vaporization of the liquid in or adjacent tochannels 52, balloons 36, or other tissue treatment tools carried on thecatheter body (such as a tissue dilation balloon, cryogenic treatmentsurface, or tissue electrode) may be used to therapeutically cooltissue. In other embodiments, despite the use of fluids which are usedas refrigerants within the body, no therapeutic cooling may be provided.The cartridge may optionally be refillable, but will often instead havea frangible seal so as to inhibit or limit re-use.

As the individual balloons may have inflated volumes that are quitesmall, cartridges that are suitable for including in a hand-held housingcan allow more than a hundred, optionally being more than a thousand,and in many cases more than ten thousand or even a hundred thousandindividual balloon inflations, despite the cartridge containing lessthan 10 ounces of fluid, often less than 5 ounces, in most cases lessthan 3 ounces, and ideally less than 1 ounce. Note also that a number ofalternative fluid sources may be used instead of or with a cartridge,including one or more positive displacement pumps (optionally such assimple syringe pumps), a peristaltic or rotary pump, any of a variety ofmicrofluidic pressure sources (such as wax or other phase-change devicesactuated by electrical or light energy and/or integrated into substrate38), or the like. Some embodiments may employ a series of dedicatedsyringe or other positive displacement pumps coupled with at least someof the balloons by channels of the substrate, and/or by flexible tubing.

Referring still to FIG. 5, processor 60 can facilitate inflation of anappropriate subset of balloons 36 of actuation array 32 so as to producea desired articulation. Such processor-derived articulation cansignificantly enhance effective operative coupling of the input 18 tothe actuated portion 20 of catheter body 12, making it much easier forthe user to generate a desired movement in a desired direction or toassume a desired shape. Suitable correlations between input commands andoutput movements have been well developed for teleoperated systems withrigid driven linkages. For the elongate flexible catheters and otherbodies used in the systems described herein, it will often beadvantageous for the processor to select a subset of balloons forinflation based on a movement command entered into a user interface 66(and particularly input 18 of user interface 66), and on a spatialrelationship between actuated portion 20 of catheter 12 and one or morecomponent of the user interface. A number of differing correlations maybe helpful, including orientational correlation, displacementcorrelation, and the like. Along with an input, user interface 66 mayinclude a display showing actuated portion 20 of catheter body 12, andsensor 63 may provide signals to processor 60 regarding the orientationand/or location of proximal base 21. Where the relationship between theinput, display, and sensor are known (such as when they are all mountedto proximal housing 14 or some other common base), these signals mayallow derivation of a transformation between a user interface coordinatesystem and a base coordinate system of actuated portion 20. Alternativesystems may sense or otherwise identify the relationships between thesensor coordinate system, the display coordinate system, and/or theinput coordinate system so that movements of the input result incatheter movement, as shown in the display. Where the sensor comprisesan image processor coupled to a remote imaging system (such as afluoroscopy, MRI, or ultrasound system), high-contrast marker systemscan be included in proximal base 21 to facilitate unambiguousdetermination of the base position and orientation. A battery or otherpower source (such as a fuel cell or the like) may be included inhousing 14 and coupled to processor 60, with the housing and catheteroptionally being used as a handheld unit free of any mechanical tetherduring at least a portion of the procedure. Nonetheless, it should benoted that processor 60 and/or sensor 63 may be wirelessly coupled oreven tethered together (and/or to other components such as a separatedisplay of user interface 66, an external power supply or fluid source,or the like).

Regarding processor 60, sensor 63, user interface 66, and the other dataprocessing components of system 10, it should be understood that thespecific data processing architectures described herein are merelyexamples, and that a variety of alternatives, adaptations, andembodiments may be employed. The processor, sensor, and user interfacewill, taken together, typically include both data processing hardwareand software, with the hardware including an input (such as a joystickor the like that is movable relative to housing 14 or some other inputbase in at least 2 dimensions), an output (such as a medical imagedisplay screen), an image-acquisition device or other sensor, and one ormore processor. These components are included in a processor systemcapable of performing the image processing, rigid-body transformations,kinematic analysis, and matrix processing functionality describedherein, along with the appropriate connectors, conductors, wirelesstelemetry, and the like. The processing capabilities may be centralizedin a single processor board, or may be distributed among the variouscomponents so that smaller volumes of higher-level data can betransmitted. The processor(s) will often include one or more memory orstorage media, and the functionality used to perform the methodsdescribed herein will often include software or firmware embodiedtherein. The software will typically comprise machine-readableprogramming code or instructions embodied in non-volatile media, and maybe arranged in a wide variety of alternative code architectures, varyingfrom a single monolithic code running on a single processor to a largenumber of specialized subroutines being run in parallel on a number ofseparate processor sub-units.

Referring now to FIG. 5A, an alternative actuation array and fluidsupply system are shown schematically. As in the above embodiment,balloons 36 are affixed along a major surface of substrate 38,optionally prior to rolling the substrate and mounting of the actuationarray to the skeleton of the catheter body. In this embodiment, eachballoon has an associated dedicated channel 52 of substrate 38, and alsoan associated valve 90. Processor 60 is coupled with valves 90, and byactuating a desired subset of the valves the associated subset ofballoons can be inflated or deflated. In some embodiments, each valvecan be associated with more than one balloon 36, so that (for example),opening of a single valve might inflate a plurality (optionally 2, 3, 4,8, 12, or some other desired number) of balloons, such as laterallyopposed balloons so as to elongate the distal portion of the catheter.In these or other embodiments, a plurality of balloons (2, 3, 4, 5, 8,12, or another desired number) on one lateral side of the catheter couldbe in fluid communication with a single associated valve 90 via a commonchannel or multiple channels so that opening of the valve inflates theballoons and causes a multi-balloon and multi-increment bend in the axisof the catheter. Still further variations are possible. For example, insome embodiments, channels 52 may be formed at least in-part by flexibletubes affixed within an open or closed channel of substrate 38, or gluedalong a surface of the substrate. The tubes may comprise polymers (suchas polyimide, PET, nylon, or the like), fused silica, metal, or othermaterials, and suitable tubing materials may be commercially availablefrom Polymicro Technologies of Arizona, or from a variety of alternativesuppliers. The channels coupled to the proximal end of the actuatablebody may be assembled using stacked fluidic plates, with valves coupledto some or all of the plates. Suitable electrically actuated microvaluesare commercially available from a number of suppliers. Optionalembodiments of fluid supply systems for all balloon arrays describedherein may have all values mounted to housing 14 or some other structurecoupled to and/or proximal of) the proximal end of the elongate flexiblebody. Advantageously, accurately formed channels 52 (having sufficientlytight tolerance channel widths, depths, lengths, and/or bends or otherfeatures) may be fabricated using microfluidic techniques, and may beassembled with the substrate structure, so as to meter flow of theinflation fluid into and out of the balloons of all of the actuationarrays described herein.

Referring now to FIGS. 5B and 5C, two alternative substrate layerstructures and valves are shown schematically. A variety of knownlab-on-a-chip and lab-on-a-foil production techniques can be used toassemble and seal the substrate layers, with many embodiments employingthermal fusion bonding, solvent bonding, welding (and particularlyultrasound welding), UV-curable adhesives, contact adhesives,nano-adhesives (including doubly cross-linked nano-adhesive or DCNA),epoxy-containing polymers (including polyglycidyl methacrylate), plasmaor other surface modifications, and/or the like between layers. For highfluid pressure systems, third generation nano-adhesive techniques suchas CVD deposition of less than 400 nanometer layers of DCNA materialsmay facilitate the use of high-strength polymer materials such as PET.Channels of such high-pressure systems may optionally be defined atleast in part by PET and/or fused silica tubing (which may be supportedby a substrate along some or all of the channel, and/or may be bundledtogether with other fused silica tubing along some or all of its lengthideally in an organized array with tubing locations corresponding to theballoon locations within the balloon array, analogous to theorganization of a coherent fiber optic bundle), or the like. As shown inthe embodiment of FIG. 5B, any valves (such as valve 90 a) mounted tothe substrate of the balloon array may be electrically actuated usingconductive traces 73 deposited on a surface of a substrate layer (suchas layer 70) prior to bonding, with an overlying layer (such as layer72) sealing the traces in the interior of the substrate. A valve member91 of valve 90 may move when a potential is applied to an actuationmaterial 93 using the traces, with that material optionally comprising ashape-memory alloy, piezoelectric, an electrically actuated polymer, orthe like. Still further alternative actuation materials may includephase change materials such as wax or the like, with the phase changebeing induced by electrical energy or optical energy (such as laserlight transmitted via an optical fiber or printed pathway between layersof the substrate). In some embodiments, the actuation material and valvemember may be formed using 3-D printing techniques. Multiplex circuitrymay be included in, deposited on a layer of, or affixed to substrate 38so that the number of electrical traces extending proximally alongcatheter body 12 may be less than the number of valves that can beactuated by those valves. The valves may take any of a wide variety offorms, and may employ (or be derived from) known valve structures suchas known electrostatically-actuated elastomeric microfluidic valves,microfluidic polymer piston or free-floating gate valves, layeredmodular polymeric microvalves, dielectric elastomer actuator valves,shape memory alloy microvalves, hydrogel microactuator valves,integrated high-pressure fluid manipulation valves employing paraffin,and the like. Along with electrically actuated microvalves, suitablevalves may be optically actuated, fluid actuated, or the like.

Regarding FIG. 5C, an alternative fluid-actuated valve includes anelastomeric layer 77 between a balloon inflation channel 52 and atransverse actuation channel 75. As is often done in commercialmicrofluidic structures, fluid pressure in the actuation channel canpush the elastomeric layer 52 into channel 52 to sufficiently seal theballoon inflation channel 52 to inhibit flow, here to inhibit into orout of the balloon. The actuation fluid flow may be from the sameoriginal fluid source as the balloon inflation fluid or a differentsource, and may be at a different pressure. Still further transverseactuation fluid channels and valves may be provided so as to allowcontrol over a greater number of balloons than there are channels in atleast the proximal portion of the catheter.

It should be understood that many of the valves shown herein areschematic, and that additional or more complex valves and channelsystems may be included to control inflation and deflation of theballoons. One or more valves in the system may comprise gate valves(optionally normally closed, normally open or stable), so as to turninflation fluid flow from the fluid source to at least one balloon on oroff Deflation may optionally be controlled by a separate gate valvebetween each balloon (or groups of balloons) and one or more deflationport of substrate 38 (the fluid from the balloon optionally exiting fromthe substrate to flow proximally between radially inner and outer sealedlayers of the catheter) or housing 14. Alternative 2-way valves mayallow i) communication between either the fluid source and the balloon(with flow from the balloon being blocked), or ii) between the balloonand the deflation outflow (with the flow from the fluid source beingblocked). Still further alternatives may be employed, including a 3 wayvalve having both of the above modes and iii) a sealed balloon mode inwhich the balloon is sealed from communication with the fluid source andfrom the deflation outflow (with flow from the source also beingclosed).

Referring now to FIG. 6A, an alternative embodiment of catheter body 12includes a substrate 38 with balloons 36 extending radially inwardlyfrom the substrate. Lateral edges of substrate 36 may be affixedtogether at least intermittently (particularly axially along balloons36) so as to limit radial expansion of the substrate (and therebyballoons 36 from migrating radially out from between the loops of theskeleton). Referring now to FIG. 6B, yet another alternative embodimentof catheter body 12 has both an inner helical coil 92 (disposed radiallyinward of substrate 38), and an outer helical coil 34 (disposed radiallyoutward of the substrate). The inner coil may help keep the balloons andsubstrate from migrating inward from the desired position, with ourwithout affixing the edges of the substrate together.

Referring now to FIGS. 6C-6H, optional catheter structures employ analternative balloon array structure having one or more elongate balloons96, 204 that each extend axially, with the balloons here being formed ina layered substrate 208 so that the balloons together define a balloonarray 206 that can frictionally engage or latch against coils to helpinhibit lateral bending of a catheter body. When deflated, the loops 42,100, 202 of the helical coils can move away from (or if separated,toward) each other, allowing the catheter body to flex (and straighten).In contrast, fluid expansion of balloons 204 causes each axial balloonto radially engage a plurality of coils 202, inhibiting movement of thecoils toward or away from each other so as to add axial stiffness to thecatheter body. Interestingly, this can make it more difficult to bend astraight portion of the catheter, and/or can make it more difficult fora bent portion of the catheter to straighten (or otherwise alter itsaxial configuration). As described above, substrate 38, 208 may bedisposed between inner and outer coils so that the axially orientedballoons radially engage either (or both); or the substrate may bedisposed radially outward of the coil to be engaged with the edges ofthe substrate affixed together so as to limit radial displacement of theballoons and promote firm radial engagement between the expanded balloonand the coil. Still further alternatives are available, including theuse of semi-rigid or other radial support materials in the substrate,with or without edges affixed together. As can also be understood withreference to FIGS. 4C and 6A, bend-inducing balloons may be combinedwith bend-inhibiting balloons by including both types of balloons on asingle substrate (optionally on opposed sides) or on separatesubstrates. Advantageously, the substrate, balloon, and fluid supply andcontrol structures of these bend-change-inhibiting balloon arrays mayinclude the characteristics described above for the correspondingstructures of the balloon articulation systems. Note that the simplifiedschematic stiffening balloon array of FIG. 6D is merely representative(showing axial overlap of sets of three balloons, with the sets offsetto allow continuous stiffening throughout a segment). To facilitatebending of the segment when the balloons are not inflated, the substratemay have lateral cuts 56 (as shown in FIG. 5), the array may be arrangedin partially overlapping substrate areas with substrate/substratesliding between the balloons 96 (such as by using a helical substratearrangement as may be understood with reference to FIGS. 7G and 7I), orthe like.

Referring now to FIGS. 6E and 6H, an alternative local stiffening system200 includes a helical coil 202 defining an axis and one or more balloon204, with the balloon often being included in a balloon array structure206 having an array of balloons, a substrate 208, channels within oraffixed to the substrate, and the like. Substrate 208 is also used toform a circumferential band encircling the coil and some or all of theballoons and disposed radially outward of the coil 202, typically byaffixing the edges of the substrate together when rolled, forming thesubstrate using tube material, or the like. As the balloon iseffectively held radially between the coil and this band of substratematerial, expansion of the balloon can induce circumferential tension inthe band. The band can thus act as a radial hoop support, even if formedof a flexible material, so that the expanded balloon is maintained ifsufficient engagement with the adjacent loops of the coil to inhibitaxial sliding therebetween. Note that if the catheter or other elongatebody is axially bent prior to balloon expansion (as shown in FIG. 6H)the inflation of balloon 204 may be used to help inhibit changes to thatbent configuration. The inflated balloon may, however, be at leastsomewhat biased to assume a straight shape, so that there may beadvantages to limiting the axial length of each balloon to less than 3times the overall diameter of the catheter (optionally being less than 2times), though other embodiments may use longer stiffening balloons.

As can be understood with reference to FIGS. 6A-6E, axial movementinhibiting features or surfaces may be included on the stiffeningballoons or coils or both so as to limit any movement between theexpanded balloons and the loops they engage. As shown, the coil mayinclude one or more radially oriented protruding feature or edge.Alternatively (or in combination), the balloons may have protrudingfeatures or ribs, and/or one or both corresponding engagement surfacesmay comprise a high friction or stiction surface.

As shown in FIGS. 6F and 6G, in some embodiments of the stiffeningand/or articulation balloon array structures described herein, balloons210 may optionally be formed separately from the array substrate 212,optionally using known techniques for blowing non-compliant medicalballoons from tube material or the like. Such balloons may be affixed tosubstrate 212 at least in part by bonding the balloon between a first(optionally thicker) layer of the substrate 214 and a second (optionallythinner) substrate layer 216. Second layer 216 may primarily conform tothe shape of the first layer, balloons 210, and optionally anyseparately formed tubing used for channels of the fluid supply system,with the second layer optionally comprising a polymer such as athermoplastic that can shaped using heating and differential pressure.Second layer 216 may be more compliant than first layer 214, so that theballoon expands from substrate 212 primarily in the direction of secondlayer 216. Second layer 216 may optionally be more resilient than firstlayer 212, and/or may have a surface 218 that has a relatively highfriction or stiction. When used in a selective stiffening balloon arraystructure, a third layer of polymer having a low friction or stictionsurface 220 may also be included in the substrate array, with secondlayer being between the first and third layers. When balloon 210 is in adeflated configuration, high-stiction or friction surface 220 may berecessed below the third lay so that the adjacent loops of the coil arefree to move relative to each other despite any incidental contact withthe low friction surface of third layer 220. When balloon 210 isinflated, the high stiction or friction surface 218 of second layer 216is exposed so as to engage the loops of the coil, thereby inhibitingrelative movement of the coils (including changing of axial offsetsbetween the coils) and bending of the skeleton axis adjacent the engagedloops.

Referring now to FIGS. 6I, 6J, and 6L, yet another alternative arraystructure 102 includes apertures 104 through a substrate 106 around acircumferential portion (but not completely surrounding) at least someof balloons 36. The apertures 104 define tabs of substrate material 108,balloons 36, and adjacent channel portions 52 (seen in FIG. 6I) that canbe bent radially from the adjacent substrate material before or afterthe substrate has been rolled to the circumferential configuration(shown in FIG. 6J). This facilitates forming expandable balloon wallsfrom the layers of the substrate (optionally by locally decreasing athickness of one or both adjacent substrate layers along an interface,locally heating and inflating the heated substrate material within moldsto form balloon walls. As with other rolled substrate structures,lateral incisions 56 (shown in FIG. 5) and/or a helical rolled substrateconfiguration with sliding between any overlapping substrate regions mayhelp maintain flexibility of the assembly.

Referring to FIGS. 6K and 6L, details of the interface surfaces betweenthe balloons and the adjacent coils can be seen. Each axial bending orelongation balloon 36 will typically be disposed between a distallyoriented surface of a proximally adjacent loop 42 i, and a proximallyoriented surface of a distally adjacent loop 42 ii. Balloons 36 often(though not always) have convex surfaces when expanded. While helicalcoils can be formed of wires or polymers with flat or even concaveproximal and distal surfaces, many helical coils are formed from roundwires having convex distal and proximal surfaces. To limit axialdeflection associated with localized deflection of the inflated balloonwalls, it will often be beneficial to distribute axial loads transmittedbetween the skeleton and the balloon over a region of the balloonsurface that is larger than that provided by convex surface to convexsurface engagement. Hence, use of coil structures having concaveproximal and distal coil surfaces (at least adjacent balloons 36) willprovide greater inflated axial stiffness. As can be understood withreference to in FIG. 10, axial loads can be distributed from a helicalcoil having a flat or convex surface using an intermediate body ormaterial 112 between the adjacent proximal skeleton surface and balloon,and/or between the adjacent distal skeleton surface and a balloon. Theintermediate material may optionally be affixed to (or even integratedinto) the balloon wall adjacent the coil, or the coil adjacent theballoon, or may be a structure that is separate from both. Theintermediate body or material 112 may have cooperating axial engagementsurfaces 114 that press against each other (directly or through adeflated balloon wall) so as to transmit axial loads with limiteddeflection when the balloon is deflated.

Also shown in FIG. 6K is an outer barrier sheath 120 disposed radiallyover the coil 34 and actuation array 32 so as to contain inflation fluidreleased from the array. The sheath 120 may have a plurality of polymerlayers 122, 124 with a separation material 126 (such as a braid, wovencloth, or felt) between the layers. A vacuum may be applied to the spacebetween the polymer layers 122, 124 by a simple manual syringe pump orthe like, and the vacuum can be monitored to verify fluid sealing in thesystem. Alternative simpler barrier sheaths may comprise a singlepolymer layer. An inner barrier sheath may be provided with or withoutthe outer barrier sheath, and one or both barrier sheaths may beintegral with substrates of one or more actuation array(s). Sealinginner and outer barrier sheaths to each other (such as substrate 38 topolymer layer 124) distally of the actuatable portion may allow thefluid inflation fluid to be released or ported from the substrate(s) soas to flow proximally around the coil, balloons, etc. between thebarrier sheaths in any or all of the embodiments described herein. Avacuum drawn between inner and outer sheaths (for example, in the areasurrounding coil 34 and balloons 36) may be used to verify sealing aboutmuch or all of the fluid handling components, with the vacuum and vacuummonitoring system generally being simpler when the used inflation fluidis transmitted proximally within channels of the substrate.

Referring now to FIGS. 6K and 6L, axial coupling of corresponding axialsurfaces 114 of the skeleton when the balloon is deflated can beunderstood. In the embodiment of FIG. 6K, the axial surfaces of theskeleton are configured to transmit axial loads indirectly through thethrough deflated balloon wall. In the embodiment of FIG. 6L, as shown bythe deflated left-most balloon 36, the radially outward axial surfaces114 of the skeleton 130 are configured to engage each-other directly.Also seen in FIG. 6L are convex surface balloon receptacle surfaces 134that can limit axial deflection by distributing axial loads over acrossthe surface of the inflated balloons 36.

As noted above, helical structural skeletons can be biased to axiallycompress and help deflate balloons. Additional passive or activestructures axial compression structures can also help maintain thearticulatable structures in the commanded configuration, with or withoutsuch helical coil biasing. In FIG. 6K, the outer barrier sheath 120comprises an axially resilient compressive sheath. The sheath istensioned axially and applies a load 140 over some or all of the lengthof the actuated portion. During use, sheath 120 may be affixed to theskeleton distally of the actuated portion 20 and proximal of theactuated portion 20 (see FIG. 1-1). To enhance shelf life, the sheathmay be shipped in a less stressed configuration and then pulledproximally and affixed to the catheter body 12 proximal of actuatedportion 20 or proximal housing 14 prior to use (see FIG. 1-1). In FIG.6L, a plurality of active pull-wires may extend along at least a portionof the actuated portion 20 of catheter 12, with the pull wires beingdistributed circumferentially around the axis of the catheter. Motors orsprings may be used to actively or passively pull the pull wires to helpdeflate the balloons and maintain the overall configuration or pose ofthe catheter despite environmental forces. A variety of alternatives maybe employed, including use of a single actively tensioned central pullwire, actively tensioning an inner or outer sheath, or the like.

Referring now to FIGS. 6M-6P, exemplary balloon geometry and fabricationtechniques can be understood. First addressing the simplified schematicof FIG. 6M, a portion of a balloon array structure 220 includes aballoon 222 and a substrate 224. Balloon 222 extends circumferentiallyaround an axis of the curved substrate (and of the associated skeleton,omitted for simplicity here) so as to define an arc angle α. As can beunderstood with reference to FIGS. 6N and 6P, balloon 222 may have afirst diameter 226, typically near a circumferential mid-portion of theballoon. The balloon diameter may taper to a smaller diameter 228 towardcircumferential ends of the balloon so as to promote balloon/coilinterface engagement throughout the arc angle, as can be understood withreference to FIG. 6P. Additionally, as balloon 222 extends radiallyoutward of substrate 224, the radial outer surface of the balloon maybenefit from having sufficient material length so that inflation of theballoon does not tend to locally flatten the substrate 224 along the arcangle α.

A tool and method to facilitate fabrication of a balloon having both avarying diameter and sufficient material along the outer surface,despite the balloon wall being formed while the substrate is in a flatconfiguration, can be understood with reference to FIG. 6O. In thisembodiment, a channel 228 has been formed in a first substrate layer230, optionally via laser micromachining, molding, or the like. Theballoon wall will primarily be defined by a second substrate layer 232,with the second layer being formed by using differential pressure tourge or blow the second layer against a tool 234. Note that while secondlayer 232 may be blown after the first and second layer are bondedtogether through channel 228, it may instead be easier to form theballoon wall prior to bonding the substrate layers. In preparation forblowing balloon 222, second layer 224 may be locally thinned to form arecess 236 in the area of the planned balloon using laser micromachiningor the like. The tool 234 may have a recess 238 and can engage thematerial of second layer 232 around the recess. The material of secondlayer 232 adjacent the recess may be heated, and sufficient pressure maybe applied to the surface of the second layer opposed to the tool toexpand and urge the material of the layer against the tool within therecess. The recess 238 may have an undulating surface as schematicallyshown so that when the substrate is assembled and curved the inflatedballoon will be pre-formed to curve about the arc angle α. The variationin balloon diameter described above can also be defined in the recess238 of tool 234, with the tool optionally having a plurality of recessesfor other balloons of the balloon array structure, passages to apply avacuum or port gasses from between the balloon material and tool. Thetool may be formed using any of a variety of 3-D printing techniques,laser micromachining, or many of the other techniques described herein.

A number of inflation fluid supply system component arrangements for usein any or all of the articulation, stiffening, and/or bend controlsystems described herein can be understood with reference to FIGS.7A-7F. As noted above, the valves, ports, and the like may be includedin a proximal housing, may be incorporated into a substrate of theballoon array, or a combination of both. First addressing a simpleinflation control arrangement 240 of FIG. 7A, a single on/off gate valve242 may be along a fluid flow path between a fluid source 244 and aballoon 246. A limited flow exhaust port 248 remains open, and openingof valve 242 allows sufficient fluid from the source to inflate balloondespite a limited flow of fluid out of limited port 248, which can havean orifice or other fixed flow restriction. When gate valve 242 isclosed, flow out of the limited port 248 allows the balloon to deflate.The two-valve arrangement 250 of FIG. 7B uses two separate gate valves242 to independently control flow into and out of the balloon, therebylimiting the loss of fluid while the balloon remains inflated and alsopreventing deflation speed from being limited more than might otherwisebe desired. While the inflow channel into the balloon and out of theballoon are shown as being separate here, both valves may instead becoupled to the inflow channel, with the deflation valve typically beingbetween the inflation valve and the balloon.

A two-way valve arrangement 260 is shown in FIG. 7C, with a two wayvalve 262 having a first mode that provides fluid communication betweensupply 244 and balloon 246, and a second mode that provides fluidcommunication between the balloon and an exhaust port 264 (while thesupply is sealed to the port and balloon).

A ganged-balloon arrangement 270 is shown in FIG. 7D, with a two wayvalve 262 between supply 244 and a plurality of balloons 272, 274, 276,. . . . Such an arrangement allows a number (typically between 2 and 10balloons) to be inflated and deflated using a single valve, which may beused when a subset of balloons are often to be inflated, such as forelongation of an axial segment, for imposing a desired base curvature(to which other incremental axial bend components may be added), forimposing multi-balloon incremental axial bend components or the like.

A transfer-bend valve arrangement 280 is shown in FIG. 7E, with two wayvalves 262 i, 262 ii each allowing inflation of an associated balloon246 i, 246 ii, respectively. Additionally, a transfer gate valve 242between balloons 246 i and 246 ii allows inflation fluid to flow fromone (or more) balloon to another (one or more) balloon. This may allow,for example, a bend associated with one balloon to be transferredpartially or fully to a bend associated with a different balloon inresponse to environmental forces against the flexible body, such as whena catheter is pushed axially within a bent body lumen (so that the bendtransfers axially), when a catheter is rotated within a bent body lumen(so that the bend transfers laterally), a combination of the two, or thelike. A transfer valve may also be used, for example, help determine acatheter shape that limits forces imposed between a surrounding lumenalwall and the catheter structure. For this (and potentially otheradvantageous uses) a valve may be opened between a full-inflationpressure source and one or more balloon to initially inflate suchballoon(s) so that the catheter is urged toward an initial state. Atleast one transfer valve may be opened between the inflated balloon(s)and one or more uninflated balloons so as to drive the catheterconfiguration having a bend. If the tissue surrounding the bend (andinternal balloon compression structures of the catheter) urge deflationof the inflated balloons with sufficient force, and if the surroundingtissue urge the catheter to assume another bend associated with thoseuninflated balloon(s) so as to mitigate the internal balloon compressionstructures of the catheter, inflation fluid can be forced from theinflated balloon(s) to the uninflated balloon(s), and the catheter canthen allow the tissue to assume a more relaxed shape. Interestingly,changes in the catheter bend configuration associated with inflationfluid flowing between balloons may at least in part be pseudo-plastic,with fluid flow resistance limiting elastic return to the prior state.Use of a flow modulating transfer valve (as opposed to a simple on/offgate valve) may allow corresponding modulation of this pseudo-plasticbend state change. Alternatively, a transfer valve and associatedchannel may have a tailored flow resistance (such as an orifice orcontrolled effective diameter section) to tailor the pseudo-plasticproperties.

A multi-pressure valve arrangement 290 is shown in FIG. 7F, in which atwo-way valve allows inflation or deflation of an associated balloonfrom a full inflation supply 244 i as described above. Alternatively, apartial inflation fluid supply 244 ii can direct fluid at a lower(optionally fixed) partial inflation pressure to the same balloon. Thepartial inflation pressure may be insufficient to overcome the bias ofthe helical coil and the like toward balloon deflation and astraight-coil configuration, and thus may not alone bend the flexiblebody (absent tissue or other environmental forces against the catheter),but can selectively reduce the strength of the catheter against a bendassociated with the partially inflated balloon. Alternatively, thepressure may be sufficient to partially inflate the balloon and induce aportion of a full-inflation bend. Regardless, one or more partialinflation fluid supply pressures may be provided using one or moreassociated valves, with the inflation fluid being a one or moreincremental pressures between a full balloon inflation pressure andatmospheric pressure. Note that partial inflation may alternatively beprovided by modulating a variable valve for a limited inflation time soas to control total fluid flow quantity to one or more balloons, bycontrolling one or more on/of pulse cycles times of a gate valve, or thelike. Still other combinations of inflation fluid directing componentsmay be included in many embodiments, with at least some of thecomponents (and particularly channels between the valves and theballoons) being integrated into the balloon array, at least some of thecomponents (particularly the pressurized fluid canister or other source)being in a proximal housing coupled to a proximal end of the catheter orother flexible body, and others (portions of the channels, valves,ports, valve actuation circuitry, etc.) being in either or distributedin both. In some embodiments, a non-actuating positive inflation fluidpressure (greater than the atmosphere surrounding the balloon array butinsufficient to separate loops of a coil) may be maintained in some orall of the balloons that are in a nominally non-inflated state. This maypre-inflate the balloons so that the fluid partially fills the balloonand the balloon wall expands where it does not engage the coil,decreasing the quantity of fluid that flows to the balloon to achievefull inflation.

A wide variety of desirable inflation fluid supply system capabilitiescan be provided using one or more valve component arrangements describedabove. For example, rather than including a separate partial inflationpressure fluid supply, a transfer valve can be used to first fullyinflate a first balloon, after which a transfer valve can be used totransfer a portion of the fluid from the inflated balloon to one or moreother balloons, resulting in gang partial inflation of multipleballoons. A fluid supply system may have a network of channels with acombination of inflation gate valves and deflation gate valves so as toallow selective inclusion of any of a plurality of individual balloonsin an inflated subset, selected ganged balloons that pre-define some orall of the members of subsets that will be used simultaneously, and thelike.

An exemplary embodiment of a helical balloon array structure 282 can beseen in FIGS. 7G-7I. Helical array 282 can be formed in a flatconfiguration and rolled helically to a cylindrical configuration.Balloons 284 may be initially formed using relatively conventionalnon-compliant balloon forming techniques, optionally with offset ends soas to facilitate affixing the balloons and inflation/deflation channels288 to a substrate 286. Balloons 284 may be relatively short (withlength/diameter aspect ratios of 4 or less), and/or may be formed ormodified so as to curve along the balloon axis (to accommodate anarc-angle curvature when the substrate is rolled and the balloons extendcircumferentially, as noted above regarding FIG. 12). Balloons 284 andtubular structures initially defining inflation/deflation channels 288may be affixed to a first substrate layer 292 using adhesive bonding,with the channels optionally comprising commercially available fusedsilica tubing. In this embodiment, balloons 284 define a 1×N array inthe flat configuration, N optionally being between 4 and 80, preferablybeing between 8 and 32, and in at least some embodiments being 16 or 24.

Elongate axes of balloons 284 are oriented so as to extendcircumferentially at an angle corresponding to a pitch angle of thehelical coil of the skeleton to be used with helical array structure 282(which will often be different than the helical pitch of substrate 286)and are positioned so that every 4^(th) (or optionally every 3^(rd))balloon is axially aligned when the substrate is rolled in thecylindrical configuration. Hence, in the rolled cylindricalconfiguration balloons 284 can define a 4×N array (or 3×N) array toallow being in 4 (+/−X and +/−Y) lateral orientations. Balloon migrationinhibiting features or tabs 294 may be affixed to the balloons (such asbeing adhesively bonded while the balloons are inflated) so that theballoons, substrate, and tabs together define coil loop receptacles 298.A second substrate layer may optionally be formed and affixed over theassembly so that the balloons, channels, and any tabs are disposedbetween the layers. Extensions of the substrate may be used asquick-disconnect fluid couplers to provide fluid communications betweenchannels 288 and the valves and fluid supply of the proximal housing.The helical substrate may facilitate flexing and elongation of thecatheter assembly, and the array can be assembled with limited tooling.Suitable fluid supply header systems may be fabricated usingcommercially available 3-D printing techniques, with the valvescomprising commercially available electrically actuated structuresmounted to the printed header and under control of a standardmicroprocessor.

Referring now to FIG. 8, components of an exemplary catheterarticulation system 292 can be seen, with these components generallybeing suitable for use in catheter system 1 of FIG. 1. In thisembodiment, a catheter 294 has a distal articulated portion 296, withthe articulated portion optionally including axially separatearticulation sub-portions or segments, and alternatively having a singlerelatively continuously articulated length. An insertion sheath/inputassembly 295 is included in the system user interface, and both assembly295 and the proximal end of catheter 294 are detachably coupleable witha proximal housing 298 using flexible cables (and quick-disconnectcouplers), with the housing containing a battery, a processor, areplaceable compressed fluid cartridge, valves, and the like. Housing298 also includes or contains additional components of the userinterface, and is sized for positioning by a single hand of a user, butneed not be moved during use of catheter 294. Commands to effectautomated bending and elongation of distal portion 296 during use mayoptionally be input into the system by bending and axial insertion ofinput 297 relative to a proximal body of the introducer sheath, therebyemploying manual movements of the user which are already familiar tophysicians that employ catheter-based diagnostic and therapeutic tools.

Regarding some of the user interface components of articulation system292, use of input 297 for controlling the articulation state of catheter294 will be described in more detail hereinbelow. In addition to input297, a number of additional (or alternative) user interface componentsmay be employed. As generally indicated above, the user interface mayinclude a housing affixed to a proximal end of catheter 294, with thehousing having a joystick as described above regarding FIG. 1-1.Trackballs or touchpads may be provided in place of a joystick, and asthe catheters and other structures described herein may have more thantwo degrees of freedom, some embodiments may include two offsetjoysticks, with a more proximal joystick on the handle being used tolaterally deflect the catheter along a proximal X-Y segment and a moredistal joystick of the same handle being used to laterally deflect thecatheter along a more distal X′-Y′ segment. These two deflections may beused to enter movement commands in a manner analogous to positioning ofa robotic base using the first joystick and then articulating a wristmounted to that base with the second joystick, with the joysticksproviding either position or velocity control input to the cathetersystem. An input wheel with a surface that rolls along the axis of thehousing can be used for entering axial elongation movement commands, andthe housing may have a circumferential wheel that can be turned by thesystem user to help provide a desired alignment between an orientationof the housing relative to the lateral deflections of the catheter asseen in the remote imaging display. Still further alternative userinterface systems may employ computer workstations such as those ofknown robotic catheter or robotic surgical systems, which may includeone or more 3-D joysticks (optionally including an input allowing 4D,5D, or even more degrees of freedom), housings mimicking those ofmechanically steerable catheter systems, or the like. As seen in theembodiment of FIG. 8, still further optional components include atouchscreen (which may show a graphical representation of distalarticulated portion 296 (one or more segments of which can betouch-selected and highlighted so that they articulate in response tomovement of input 297), pushbuttons, or the like. Still furtheralternative user interface components may include voice control, gesturerecognition, stereoscopic glasses, virtual reality displays, and/or thelike.

Referring now to FIG. 9, selected components of an articulated portion302 of an articulated catheter 304 can be seen in more detail. Aplurality of inflated balloons 306 are offset from an axis 308 ofcatheter 304 along a first lateral orientation +X, so that the balloonsurge corresponding pairs of axial (proximal and distal) surfaces on theloops of coil 310 apart. This urges the coil to bend away from inflatedballoons 306 away from the +X orientation and toward the −X lateralorientation. Uninflated balloons 312 a, 312 b, and 312 c are offset inthe lateral −X, −Y, and +Y orientations, respectively, allowingselective inflations of differing subsets of these balloons to bend axis308 in differing directions. Inflation of opposed balloons (such as −Xand +X, or −Y and +Y, or both) may elongate coil 314 along axis 308.Note that a distal portion of coil 314 has been omitted from the drawingso that the arrangement of the balloons can be more clearly seen. Thisembodiment shows relatively standard offset balloon shapes, with theaxes of the balloons bent to follow the coil. In this and otherembodiments, a single balloon between coils may impose a bend in axis308 in a range from 1 to 20 degrees, more typically being in a rangefrom 2½ to 15 degrees, and often being from 6 to 13 degrees. To allow asingle inflation lumen to achieve greater bend angles, 2, 3, 4, or moreballoon inflation lumens or ports adjacent the balloons may be in fluidcommunication with a single common fluid inflation lumen.

Referring now to FIGS. 10A-10D, an exemplary integrated balloon arrayand array substrate design and fabrication process can be understood. Asseen in FIGS. 10A and 10B, a cylinder 318 is defined having a diametercorresponding to a helical coil axis 320 of coil 310, with the coil axistypically corresponding to the central axis of the coil wire (so thatthe helical axis winds around the central axis of the elongate body).Desired balloon centerlines 322 are here defined between loops of thecoil. Alternative balloon centerlines may extend along the coil axis, ascan be understood with other embodiments described below. A flat pattern324 of the balloon centerlines 322 can be unwrapped from cylinder 318,with the flat pattern optionally forming a repeating pattern extendingalong a helical wrap of the cylinder, the helical pattern unwrapoptionally being counterwound relative to coil 310 and typically havinga pitch which is greater than that of the coil. As can be understoodwith reference to FIGS. 10C and 10D, the repeated flat pattern 324 canbe used to define a repeating substrate pattern 326, with the substratepattern here including, for each balloon in this portion of the array, aballoon portion 328, a multi-lumen channel portion 330, and a connectorportion 332 for connecting the balloon to the multi-lumen channelportion. The connector portions and balloons here extend from a singleside of the multi-lumen channel portion; alternative embodiments mayhave connector portions and balloons extending from both lateral orcircumferential sides. The loops of the substrate helix may alsooverlap. In other embodiments, the flat pattern (and associatedsubstrate and multi-lumen channels) may wind in the same direction asthe coil, with the balloons and channel structures optionally extendingalong a contiguous strip, the balloons optionally having channels alongone or both axial sides of the strip and the balloons protrudingradially from the strip and between the loops of the coil so thatconnector portions 332 may optionally be omitted. Such embodiments maybenefit from a thicker and/or polymer coil. Regardless, the helicalballoon array structure may facilitate lateral bending of the catheteralong its axis and/or axial elongation of the catheter without kinkingor damaging the substrate material along the fluid flow channels, as thesubstrate loops may slide relative to each other along an inner or outersurface of coil 310 (often within a sealed annular space between innerand outer sheaths bordering the inner and outer surfaces of thecatheter).

Advantageously, the substrate pattern may then be formed in layers asgenerally described above, with at least a portion (often the majority)of each balloon being formed from sheet material in a first or balloonlayer 334 (optionally by blowing at least a portion of the balloon fromsuitable sheet material into a balloon tool) and some or all of thechannels being formed from sheet material in a second or channel layer336. The layers can be bonded together to provide sealed fluidcommunication between the balloons and the other components of the fluidsupply system, with the outline shapes of the balloon portions 328,connector portions 332, and channel portions being cut before bonding,after bonding, or partly before and partly after. Note that a portion ofthe balloon shape may be imposed on the channel layer(s) and that aplurality of channel layers may be used to facilitate fluidcommunication between a plurality of helically separated balloons(including balloons along a single lateral orientation of the assembledcatheter) and a common fluid supply channel. Similarly, a portion (oreven all) of the channel structure might alternatively be imposed on theballoon layer, so that a wide variety of architectures are possible.Formation of multiple balloons 334 and channels 330, and bonding of thelayers can be performed using parallel or batch processing (with, forexample, tooling to simultaneously blow some or all of the balloons fora helical balloon array of an articulation sub-portion, a lasermicromachining station that cuts multiple parallel channels,simultaneous deposition of adhesive materials around multiple balloonsand channels), or sequentially (with, for example, rolling toolingand/or roll-by stations for balloon blowing, laser cutting, or adhesiveapplying tooling), or a combination of both. The number of balloonsincluded in a single helical substrate pattern may vary (typically beingfrom 4 to 80, and optionally being from 4 to 32, and often being from 8to 24). The balloons may be spaced for positioning along a singlelateral catheter bending orientations, along two opposed orientations,along three orientations, along four orientations (as shown), or thelike. Channel portion 330 may terminate at (or be integrated with) aninterface with a multi-channel cable 334 that extends proximally alongthe coil (and optionally along other proximal balloon array portionsformed using similar or differing repeating balloon substrate patterns).A wide variety of alternative balloon shapes and balloon fabricationtechniques may be employed, including blowing a major balloon portionfrom a first sheet material and a minor portion from a second sheetmaterial, and bonding the sheets surrounding the blow portions togetherwith the bond axially oriented (as shown in FIG. 10) so that the sheetsand substrate layers are oriented along a cylinder bordering the coil,or with the bond radially oriented so that the sheet material adjacentthe bonds is connected to adjacent substrate by a bent connector portionor tab.

As can be understood with reference to the balloon structures of FIG.10E-10I (and more generally as illustrated and described herein), a widevariety of alternative balloon shapes and balloon fabrication techniquesmay be employed. Balloon 340 of FIG. 10E may be formed by blowing amajor balloon portion 342 from a first sheet material and a minorportion 344 from a second sheet material, and by bonding the sheetssurrounding the blow portions together. The bond may be axially oriented(as shown in FIGS. 10A-10D) so that the sheets and substrate layers areoriented along a cylinder bordering the coil, or radially oriented (asshown in FIGS. 6L and 10E), with the radially oriented sheet materialadjacent the bonds being connected to the other array substrate by abent connector portion or tab. The balloons may have substantiallycircular cross-sections with smaller diameters near the ends asdescribed above. While bonded balloons may optionally be formed byforming similar corresponding expanded regions 346 in two sheets orlayers (as shown in FIG. 10F), there may be advantages to forming aballoon cross-section primarily in a first sheet 348 and bonding that toa second sheet with a smaller (or non) expanded region 350 (as shown inFIG. 10G). In particular, the strength of the bond may be enhanced byfolding and bonding bordering substrate material adjacent the balloonshape to the wall of the balloon as shown in FIG. 10H; this may befacilitated when a major portion of the balloon is on one side of thebond. Still further alternatives are possible, including providing asecond balloon wall layer surrounding any of the bonded balloons shownor described herein, as can be understood with reference to FIG. 10I.The bonded balloon and second balloon wall may be formed separately withsimilar shapes which will tend to maintain alignment between the walls,decreasing any reliance on high-strength bonding between the balloonmaterials.

Referring now to FIGS. 11A and 11B, an alternative coaxial balloon/coilarrangement can be understood. In these embodiments, balloons 364 aremounted over a coil 366, with a plurality of the balloons typicallybeing formed from a continuous tube of material that extends along thehelical axis of the coil (see helical axis 320 of FIG. 10A). The balloonmaterial will generally have a diameter that varies locally, with theballoons being formed from locally larger diameter regions of the tube,and the balloons being separated by sealing engagement between the tubematerial and coil therein at locally smaller diameters of the tube. Thevariation in diameter may be formed by locally blowing the balloonsoutward from an initial tube diameter, by locally heat-shrinking and/oraxially stretching the tube down from an initial tube diameter, or both,and adhesive or heat-bonding between the tube and coil core therein mayenhance sealing. In alternative embodiments, metal rings may be crimpedaround the tubular balloon material to affix (and optionally seal) thetube to the underlying helical coil, with the rings and crimpingoptionally employing marker band structures and associated techniques.Some or even all of the variation in diameter of the balloon materialalong the coil may be imposed by the crimped rings, though selectiveheat shrinking and/or blowing of the balloons and/or laser thermalbonding of the balloon to the coil may be combined with the crimps toprovide the desired balloon shape and sealing. Regardless, fluidcommunication between the inner volume of the balloon (between theballoon wall and the coil core) may be provided through a radial port toan associated lumen within the coil core. As can be understood withreference to coil assembly 360 of FIG. 11A, the balloons may have outersurface shapes similar to those described above, and may similarly bealigned along one or more lateral bending orientations. As can beunderstood with reference to assemblies 360 and 362 of FIGS. 11A and11B, bend angles and radii of curvature of the catheter adjacent theballoon arrays may be determined by an axial spacing (and/or number ofloops) between balloons, and/or by selective inflation of a subset ofballoons (such as by inflating every other balloon aligned along aparticular lateral axis, every third aligned balloon, every forthaligned balloon, and so on).

Referring now to FIGS. 11C, 11D, and 11E, alternative coaxialballoon/coil systems may take a variety of differing forms. In FIG. 11C,a plurality of helical structures 370, 372 are interleaved together. Onehelical structure 370 here takes the form of a simple helical coil andfunctions as an element of the structural backbone of a catheter,compressing balloons between loops of the coil and the like. The otherhelical structure includes balloons 374 over a helical core, with one ormore lumens extending within the helical core. Note that the helicalcore supporting the balloons may or may not include a structural coilwire or the like, so that the components that provide fluid transmissionfunctionality may be separated from or integrated with the structuralcomponents. In the embodiment of FIG. 11C, a plurality of helicalstructures each have associated balloons, which may be inflatedseparately or together. In some embodiments, balloons aligned along oneor more lateral orientations may be on a first helical structure, andballoons along one or more different orientations may be on a secondinterleaved helical structure, so that fluid transmission through ahelical core may be simplified. In other embodiments (as can beunderstood with reference to 4 direction coaxial balloon/coil 380 ofFIG. 11E), balloons subsets aligned along the differing lateralorientations may be mounted to a single helical core.

Referring now to FIGS. 11F and 11G, exemplary multi-lumen helical corestructures can be understood. In these embodiments, an extruded polymersheath is disposed over a structural coil wire 382, with the sheathhaving multiple peripheral lumens, such as 4 or 6 lumen sheath 384 or 16lumen sheath 386. A tube of balloon material may be positioned over thesheath, with larger diameter portions of the tube forming balloons 388,and smaller diameter portions 390 engaging the sheath therein so as toseal between the balloons. A port 392 can be formed through the wall ofthe sheath into one of the lumens (typically prior to completion of theballoon structure) so that the interior of the balloon is in fluidcommunication with that associate lumen. The lumen may be dedicated tothat one balloon, or will often be coupled to (and used to inflate) oneor more balloons as a group or sub-set, with the group often beingaligned along a lateral orientation of the coil so as to bend the coilin a common direction, opposed so as to axially elongate the coil, orthe like. As can be understood by comparison of FIGS. 11F and 11G, thenumber of lumens in a helical core may impact the inflation lumen size(and response time), so that there may be benefits to using separateactuation sub-portions and running fluid flow channels outside thehelical core. Where large numbers of lumens or complex lumen networksand geometries are desired, the core may include a first sheath layerhaving an outer surface which is processed (typically lasermicromachined) to form some or all of the channels. A second sheathlayer can be extruded or bonded radially over the first layer tolaterally seal the channels. Similar processing of the outer surface ofthe second layer (and optionally subsequent layers) and extrusion orbonding of a third layer (and optionally subsequent layers) radiallyover the second layer may also be performed to provide multi-layeredlumen systems.

Referring now to FIG. 12, further separation of functionality amongexemplary catheter components can be understood with reference to anexploded assembly 400, which shows an axial portion of an articulatedcatheter, the components here being laterally displaced from each other(and from their assembled coaxial positioning). The fluid-containingcomponents of this portion are preferably contained between an innersheath 402 and an outer sheath 404, with these sheaths being sealed toeach other proximally and distally of the balloon array (or of someportion of the array). By drawing a vacuum between the sealed inner andouter sheaths (optionally using a simple positive syringe pump or thelike) and by monitoring of the vacuum with a pressure sensing circuitcoupled to a fluid supply shut off-valve, integrity of the fluidtransmission and drive components within the patient body can beensured, and inadvertent release of drive fluid within the patient canbe inhibited.

Still referring to FIG. 12, a coaxial helical coil/balloon assembly 406is disposed radially between the inner and outer sheaths 402, 404. Theinner and/or outer sheaths may be configured so as to enhance radialstrength and axial flexibility, such as by including circumferentialfibers (optionally in the form of a polymer or metallic braid, loops, orwindings), axial corrugations, or the like. As described above, balloonsof assembly 406 are mounted to a helical core along a helical axis. Atleast one lumen extends along the helical core and allows the balloonson the core to be inflated and deflated. To help maintain axialalignment of the loops of assembly 406 an alignment spacer coil 408 isinterleaved between the assembly loops. Spacer coil 408 has opposedsurfaces with indented features so that axial compressive forces (fromthe environment or inflation of the balloons) squeezes the alignmentspacer and keeps the assembly balloons and adjacent loops from beingpushed radially out of axial alignment, as can be further understoodwith reference to FIGS. 6K and 6L and the associated text. Note that anyof the structural skeleton or frame elements described herein (includingthe push-pull frames described below) may include balloon/frameengagement features (such as indentations along balloon-engagingsurfaces), and/or separate balloon/frame interface bodies may beprovided between the frames and the balloons to help maintain alignmentballoon/frame alignment or to efficiently transmit and distribute loadsor both. Note that compression between loops of assembly 406 may beimposed by the coil, by the spacer, by the inner and/or outer sheath, bya pullwire, or by a combination of two or more of these. Note also thatalternative embodiments may replace the balloons mounted on the coilwith balloons between loops of the coil coupled with a layered arraysubstrate such as those shown in FIGS. 10C and 10D, optionally with apair of alignment spacer coils on either axial surface of the balloons(and hence between the balloons and the coil). Still furtheralternatives include multiple interleaved coil/balloon assemblies,and/or other components and arrangements described herein.

As there may be a large total number of balloons in the overall balloonarray of some embodiments, and as those arrays may be separated axiallyinto articulated sub-portions of an overall catheter (or otherarticulated elongate body), and as the available space within the coilcore of coil/balloon assembly 406 may be limited, it may be advantageousto have one or more separate structures extending axially within theannular space between inner and outer sheaths 402, 404. Those separatestructures can have additional fluid inflation channels that areseparate from the fluid inflation channels of the coil/balloon assemblyor assemblies, and that can be used for inflating balloon articulationarrays that are mounted distally of the coil/balloon assembly 406.Toward that end, thin flat multi-lumen helical cable structures 410 a,410 b may be disposed in the space radially between the coil/balloonassembly 406 and outer sheath 404, and/or between the coil/balloonassembly and inner sheath 402. Cables 410 may comprise a series of smalldiameter tubular structures (optionally comprising PET or fused silicawith appropriate cladding) which may or may not be affixed together andare in a side-by-side alignment, a multichannel structure formed bymicromachining and bonding layers (as described above), a multi-lumenextrusion having an elongate cross-section, or the like. Each cable 410a, 410 b of a particular axial segment may be coupled to a core of acoil/balloon assembly for a more distal articulated axial segment. Ahelical or serpentine configuration of the cables may facilitate axialbending and/or elongation without stressing the cables, and the numberof cables along an articulation segment may range from 0 (particularlyalong a distal articulation segment) to 10. Note that a number ofalternative arrangements are also possible, including separating thecables from the coil/balloon assembly with an intermediate sheath,enhancing flexibility by using a number of separate fused silica tubeswithout bundling subsets of the tubes into cables, and the like.

As can be understood with reference to FIG. 13A one or more stiffeningballoons may be incorporated into the cable structure, with thestiffening balloons of each segment optionally being in fluidcommunication with a common supply lumen, and optionally with a commonsupply lumen for one, some, or all other segments. In the exemplarycable structure shown, the stiffening balloon may comprises a tubularmaterial disposed around a multi-lumen cable extrusion, and may beinflated using a port within the tube into a selected lumen of theextrusion. The stiffening balloon tube may be sealed to the cableextrusion or the like proximally and distally of the port, and may havean expandable length sufficient to extend along some or all of an axialarticulation segment or sub-portion. The cables and any stiffeningballoons thereon may extend axially between the coil and an inner orouter sheath, inflation of such stiffening balloons can induce radiallyengagement between the stiffening balloons and the coil, inhibitingchanges in the offsets between loops and thereby stiffening the catheteragainst axial bending. The stiffening balloon may be inflated atpressures significantly lower than the bending or elongation actuationballoons, and may be used along segments or even catheters lackingbending or elongation balloons altogether. Alternatively, the cable mayoften be omitted, particularly where the core along a single segment canencompass sufficient channels for the desired degrees of freedom of thecatheter.

Referring now to FIGS. 13B and 13C, one exemplary transition from amulti-lumen helical core to a cable can be understood. The helical corehere again includes a coil wire 420 surrounded by an extrudedmulti-lumen polymer body 422, with the body here having lumens 424 thattwist around the coil wire. While only 3 lumens are shown, the spacinghere would allow for 9 twisting lumens (the other lumens being omittedfor simplicity). Radial ports from 8 of these lumens would allow, forexample, independent inflation control over 8 balloons (or groups ofballoons), and the ninth lumen may be used to draw and monitor a vacuumin a sealed axial segment around these balloons and between inner andouter sheaths (both as described above). Additionally, in the spacebetween two adjacent lumens a notch 426 extends radially part waythrough body 422, with the notch winding around the core axis.Proximally of the most proximal balloon mounted on body 422, body 422 isseparated at notch 426 and the body material and the lumens 424 thereinare unwound from the coil wire 420. This unwound material can beflattened to form a multi-lumen cable as explained above regardingcables 410, 410 a, and 410 b of FIGS. 12 and 13, with the cableextending proximally from a helical multi-lumen core without having torely on sealed tubular joints between the cable and the helical core orthe like. Alternative bonded joints or connectors between an extrusion,a single or multi-lumen tubular structure, and/or a layered channelsystem may also be employed.

Referring now to FIG. 13, an exemplary catheter 430 has an articulatedportion 432 that includes a plurality of axially separate articulatedsegments or sub-portions 434 a, 434 b, 434 c, and 434 d. Generally, theplurality of articulation segments may be configured to facilitatealigning a distal end of the catheter with a target tissue 436. Suitablearticulation segments may depend on the target tissue and plannedprocedure. For example, in this embodiment the articulation segments areconfigured to accurately align a distal end of the catheter with theangle and axial location of the native valve tissue, preferably for anypatient among a selected population of patients. More specifically, thecatheter is configured for aligning the catheter axis at the distal endof the catheter with (and particularly parallel to) an axis of thetarget tissue, and (as measured along the axis of the catheter) foraxially aligning the end of the catheter with the target tissue. Suchalignment may be particularly beneficial, for example, for positioning aprosthetic cardiac valve (optionally an aortic valve, pulmonary valve,or the like, and particularly a mitral valve) with tissues of oradjacent a diseased native valve. Suitable catheter articulationcapabilities may also, in part, depend on the access path to the targettissue. For alignment with the mitral valve, the catheter may, forexample, be advanced distally into the right atrium via the superior orinferior vena cava, and may penetrate from the right atrium through theseptum 438 into the left atrium. Suitable transceptal access may beaccomplished using known catheter systems and techniques (thoughalternative septal traversing tools using the articulated structuresdescribed herein might alternatively be used). Regardless, to achievethe desired alignment with the native valve tissue, the catheter may beconfigured to, for example: 1) from distally of (or near) the septum,form a very roughly 90 degree bend (+/−a sufficient angle so as toaccommodate varying physiologies of the patients in the population); 2)extend a distance in desired range in three dimensions, including a)apically from the septal penetration site and b) away from the plane ofthe septal wall at the penetration; and 3) orient the axis of thecatheter at the distal end in three dimensions and into alignment withthe native valve tissue.

To achieve the desired alignment, catheter 430 may optionally provideconsistent multi-axis bend capabilities as well as axial elongationcapabilities, either continuously along the majority of articulatableportion 432 of catheter 430, or in articulated segments at regularintervals extending therealong. Alternative approaches may employ morefunctionally distinguished articulation segments. When present, eachsegment may optionally have between 4 and 32 balloons, subsets of theballoons within that segment optionally being oriented along from 1 to 4lateral orientations. In some embodiments, the axis bending balloonswithin at least one segment may all be aligned along a single bendorientation, and may be served by a single inflation lumen, often servedby a modulated fluid supply that directs a controlled inflation fluidvolume or pressure to the balloons of the segment to control the amountof bending in the associated orientation. Alternative single lateralbending direction segments may have multiple sets of balloons served bydifferent lumens, as described above. For example, segments 434 a and434 b may both comprise single direction bending segments, each capableof imposing up to 60 degrees of bend angle and with the former having afirst, relatively large bend radius in the illustrated configuration dueto every-other axial balloon being inflated (as can be understood withreference to FIG. 11A) or due to inflation with a limited quantity ofinflation fluid. In segment 434 b, all but the distal-most four balloonsmay be inflated, resulting in a smaller bend radius positioned adjacentsegment 434 a, with a relatively straight section of the catheter distalof the bend. Segment 434 c may have balloons with four different bendorientations at a relatively high axial density, here having selectedtransverse balloons (such as 6+X balloons and 2−Y balloons) inflated soas to urge the catheter to assume a shape with a first bend componentaway from the septal plane and a second bend component laterally awayfrom the plane of the bends of segments 434 a and 434 b. Segment 434 dmay comprise an axial elongation segment, with opposed balloons in fluidcommunication with the one or more inflation fluid supply lumen of thissegment. Axial positioning of the end of the catheter may thus beaccurately controlled (within the range of motion of the segment) byappropriate transmission of inflation fluid. Advantageously, suchspecialized segments may limit the number of fluid channels (and thecost, complexity and/or size of the catheter) needed to achieve adesired number of degrees of freedom and a desired spatial resolution.It should be understood that alternative segment arrangements might beemployed for delivery of a prosthetic heart valve or the like, includingthe use of three segments. The valve might be positioned using athree-segment system by, for example, inserting the catheter so that theseptum is positioned along the middle of the three segments, ideallywith the catheter traversing the septum at or near the middle of themiddle segment.

Referring now to FIGS. 14A-14C, a still further embodiment of anarticulated catheter includes first and second interleaved helicalmulti-lumen balloon fluid supply/support structures 440 a, 440 b, alongwith first and second resilient helical coils 442 a, 442 b. In thisembodiment, a series of balloons (not shown) are mounted around each ofthe multi-lumen structures, with the balloons spaced so as to be alignedalong three lateral bending orientations that are offset from each otheraround the axis of the catheter by 120 degrees. Six lumens are providedin each multi-lumen structure, 440 a, 440 b, with one dedicatedinflation lumen and one dedicated deflation lumen for each of the threelateral bending orientations. Radial fluid communication ports betweenthe lumens and associated balloons may be provided by through cutsthrough pairs of the lumens.

By spacing the cuts 444 a, 444 b, 444 c, as shown, and by mountingballoons over the cuts, the inflation and deflation lumens can be usedto inflate and deflate a subset of balloons aligned along each of thethree bending orientations. Advantageously, a first articulated segmenthaving such a structure can allow bending of the catheter axis in anycombination of the three bend orientations by inflating a desired subsetof the balloons along that segment. Optionally, the bend angle for thatsubset may be controlled by the quantity and/or pressure of fluidtransmitted to the balloons using the 6 lumens of just one multi-lumenstructure (for example, 440 a), allowing the segment to function in amanner analogous to a robotic wrist. Another segment of the catheteraxially offset from the first segment can have a similar arrangement ofballoons that are supplied by the 6 lumens of the other multi-lumenstructure (in our example, 440 b), allowing the catheter to position andorient the end of the catheter with flexibility analogous to that of aserial wrist robotic manipulators. In other embodiments, at least someof the balloons supplied by the two multi-lumen structures may axiallyoverlap, for example, to allow increasing bend angles and/or decreasingbend radii by combining inflation of overlapping subsets of theballoons. Note also that a single lumen may be used for both inflationand deflation of the balloons, and that multi-lumen structures of morethan 6 lumens may be provided, so that still further combinations thesedegrees of freedom may be employed.

In the embodiment illustrated in the side view of FIG. 14A and in thecross-section of FIG. 14B, the outer diameter of the helical coils isabout 0.130 inches. Multi-lumen structures 440 a, 440 b have outerdiameters in a range from about 0.020 inches to about 0.030 inches(optionally being about 0.027 inches), with the lumens having innerdiameters of about 0.004 inches and the walls around each lumen having aminimum thickness of 0.004 inches. Despite the use of inflationpressures of 20 atm or more, the small diameters of the lumens helplimit the strain on the helical core structures, which typicallycomprise polymer, ideally being extruded. Rather than including aresilient wire or the like in the multi-lumen structure, axialcompression of the balloons (and straightening of the catheter axisafter deflation) is provided primarily by use of a metal in coils 442 a,442 b. Opposed concave axial surfaces of coils 442 help maintain radialpositioning of the balloons and multi-lumen structures between thecoils. Affixing the ends of resilient coils 442 and balloonsupply/support structures 440 together to the inner and outer sheaths atthe ends of the coils, and optionally between segments may help maintainthe helical shapes as well. Increasing the axial thickness of coils 442and the depth of the concave surfaces may also be beneficial to helpmaintain alignment, with the coils then optionally comprising polymerstructures. Still other helical-maintaining structures may be includedin most or all of the helical embodiments described herein, includingperiodic structures that are affixed to coils 442 or other helicalskeleton members, the periodic structures having protrusions that extendbetween balloons and can engage the ends of the inflated balloon wallsto maintain or index lateral balloon orientations.

Many of the embodiments described herein provide fluid-drivenarticulation of catheters, guidewires, and other elongate flexiblebodies. Advantageously, such fluid driven articulation can rely on verysimple (and small cross-section) fluid transmission along the elongatebody, with most of the forces being applied to the working end of theelongate body reacting locally against the surrounding environmentrather than being transmitted back to a proximal handle or the like.This may provide a significant increase in accuracy of articulation,decrease in hysteresis, as well as a simpler and lower cost articulationsystem, particularly when a large number of degrees of freedom are to beincluded. Note that the presence of relatively high pressure fluid,and/or low temperature fluid, and/or electrical circuitry adjacent thedistal end of an elongate flexible body may also be used to enhance thefunctionality of tools carried by the body, particularly by improving oradding diagnostic tools, therapeutic tools, imaging or navigationstools, or the like.

Referring now to FIG. 15, a radially elongate polymer helical ballooncore structure 450 generally has a cross section with a radial thickness452 that is significantly greater than its axial thickness 454. Radialthickness 452 may optionally be, for example 80% or more of the inflateddiameter of the surrounding balloon, while axial thickness 454 may bebetween 20% and 75% of the inflated diameter. As compared to a circularcore cross-section, such an elongate cross-section provides additionalterritory for balloon lumens extending within the coil core (allowingmore lumens and separately inflatable balloons or groups of balloons,and/or allowing larger lumen sizes for faster actuation times) with thesame the axial actuation stroke of the surrounding balloon. Theexemplary cross-sectional shapes include elliptical or othercontinuously curved shapes to facilitate sealing engagement with thesurrounding balloon wall material, with an alternative having proximaland distal regions with circular curvatures corresponding to those ofthe inflated balloon (so as to enhance axially compressive forcetransmission against an axially indented coil spring surface configuredto evenly engage the inflated balloon).

Referring now to FIG. 16, a perspective view of an exemplary introducersheath/input assembly for use in the systems of FIGS. 1 and 8 can beseen in more detail. Introducer/input assembly 460 generally includes anintroducer sheath assembly 462 and an input assembly 464. Introducer 462includes an elongate introducer sheath 466 having a proximal end 468 anda distal end 470 with an axial lumen extending therebetween. A proximalhousing 472 of introducer 462 contains an introducer hemostasis valve.Input 464 includes a flexible joystick shaft 474 having a distal endslidably extending into the lumen of introducer housing 472, and aproximal end affixed to an input housing 476 containing an input valve.A lumen extends axially through input 464, and an articulatable catheter480 can be advanced through both lumens of assembly 460. A cable orother data communication structure of assembly 460 transmits movementcommands from the assembly to a processor of the catheter system so asto induce articulation of the catheter within the patient. Morespecifically, when the catheter system is in a driven articulation mode,and a clutch input 482 of introducer/input assembly 460 is actuated,movement of input housing 476 relative to sheath housing 472 inducesarticulation of one or more articulatable segment of catheter 480 nearthe distal end of the catheter, with the catheter preferably having anyone or more of the articulation structures described herein. The valveswithin the housings of introducer/input assembly may be actuatedindependently to axially affix catheter 480 to introducer 462, and/or toinput 464.

Referring now to FIGS. 17A and 17B, articulation system componentsrelated to those of FIGS. 14A-14C can be seen. Two multi-lumen polymerhelical cores 440 can be interleaved with axially concave helicalsprings along the articulated portion of a catheter. Curved transitionzones extend proximal of the helical cores to axially straightmulti-lumen extensions 540, which may extend along a passive(unarticulated) section of the catheter, or which may extend througharticulated segments that are driven by fluid transmitted by otherstructures (not shown). Advantageously, a portion of each proximalextension 540 near the proximal end can be used as a proximal interface550 (See FIG. 17C), often by employing an axial series of lateral portsformed through the outer walls of the multi-lumen shaft into the variouslumens of the core. This proximal interface 550 can be mated with areceptacle 552 of a modular valve assembly 542 so as to provide sealed,independently controlled fluid communication and a controlled flow ofinflation fluid to desired subsets of the balloons from a pressurizedinflation fluid source, along with a controlled flow of exhaust fluidfrom the balloons to the atmosphere or an exhaust fluid reservoir.

Extensions 540 extend proximally into a valve assembly 542 so as toprovide fluid communication between fluid pathways of the valve assemblyand the balloons of the articulated segment. Valve assembly 542 includesan axial series of modular valve units 542 a, 542 b, 542 c, etc.Endplates and bolts seal fluid paths within the valve assembly and holdthe units in place. Each valve assembly 542 includes at least one fluidcontrol valve 544, and preferably two or more valves. The valves maycomprise pressure modulating valves that sense and control pressure,gate valves, three-way valves (to allow inflation fluid along a channelto one or more associated balloons, to seal inflation fluid in theinflation channel and associated balloons while flow from the fluidsource is blocked, and to allow inflation fluid from the channels andballoons to be released), fluid dispersing valves, or the like. O-ringsprovide sealing between the valves and around the extensions 540, andunthreading the bolts may release pressure on the O-rings and allow theextensions to be pulled distally from the valve assembly, therebyproviding a simple quick-disconnect capability. Radial ports 546 areaxially spaced along extensions 540 to provide fluid communicationbetween the valves and associated lumens of the multi-lumen polymerextensions, transitions, and helical coils. Advantageously, where agreater or lesser number of inflation channels will be employed, more orfewer valve units may be axially stacked together. While valves 544 arehere illustrated with external fluid tubing connectors (to be coupled tothe fluid source or the like), the fluid paths to the valves mayalternatively also be included within the modular valve units, forexample, with the fluid supply being transmitted to each of the valvesalong a header lumen that extends axially along the assembly and that issealed between the valve units using additional O-rings or the like.

Referring now to FIG. 18, a simplified manifold schematic shows fluidsupply and control components of an alternative manifold 602. Asgenerally described above, manifold 602 has a plurality of modularmanifold units or valve assembly plates 604 i, 604 ii, . . . stacked inan array. The stack of valve plates are sandwiched between a front endcap 606 and a back end-cap 608, and during use the proximal portion ofthe multi-lumen conduit core(s) extend through apertures in the frontcap and valve plates so that the proximal end of the core is adjacent toor in the back cap, with the apertures defining a multi-lumen corereceptacle. The number of manifold units or modules in the stack issufficient to include a plate module for each lumen of each of themulti-lumen core(s). For example, where an articulatable structure has 3multi-lumen core shafts and each shaft has 6 lumens, the manifoldassembly may include a stack of 6 plates. Each plate optionally includesan inflation valve and a deflation valve to control pressure in one ofthe lumens (and the balloons that are in communication with that lumen)for each multi-lumen shaft. In our 3-multi-lumen shaft/6 lumen eachexample, each plate may include 3 inflation valves (one for a particularlumen of each shaft) and 3 deflation valves (one for that same lumen ofeach shaft). As can be understood with reference to the multi-lumenshaft shown in receptacle 1 of FIG. 18, the spacing between the portsalong the shaft corresponds to the spacing between the fluid channelsalong the receptacle. By inserting the core shaft fully into themulti-lumen shaft receptacle, the plate channel locations can beregistered axially with the core, and with the ports that were drilledradially from the outer surface of the multi-lumen core. The processorcan map the axial locations of the valves along the receptacle with theaxial locations of the ports along the core shafts, so that a port intoa particular lumen of the core can be registered and associated with afluid channel of specific inflation and deflation valves. One or moreinflation headers can be defined by passages axially through thevalve-unit plates; a similar deflation header (not shown) can also beprovided to monitor pressure and quantity of fluid released from thelumen system of the articulated device. O-rings can be provided adjacentthe interface between the plates surrounding the headers andreceptacles. Pressure sensors (not shown) can monitor pressure at theinterface between each plate and the multi-lumen receptacle.

Along with monitoring and controlling inflation and deflation of all theballoons, manifold 602 can also include a vacuum monitor system 610 toverify that no inflation fluid is leaking from the articulated systemwithin the patient body. A simple vacuum pump (such as a syringe pumpwith a latch or the like) can apply a vacuum to an internal volume orchamber of the articulated body surrounding the balloon array.Alternative vacuum sources might include standard operating room vacuumsupply or more sophisticated powered vacuum pumps. Regardless, if thevacuum degrades the pressure in the pressure in the chamber of thearticulated structure will increase. In response to a signal from apressure sensor coupled to the chamber, a shut-off valve canautomatically halt the flow of gas from the canister, close all ballooninflation valves, and/or open all balloon deflation valves. Such avacuum system may provide worthwhile safety advantages when thearticulated structure is to be used within a patient body and theballoons are to be inflated with a fluid that may initially take theform of a liquid but may vaporize to a gas. A lumen of a multi-lumencore shaft may be used to couple a pressure sensor of the manifold to avacuum chamber of the articulated structure via a port of the proximalinterface and an associated channel of the manifold assembly, with thevacuum lumen optionally comprising a central lumen of the multi-lumenshaft and the vacuum port being on or near the proximal end of themulti-lumen shaft.

Further alternative manifold structures may include a stack of valveunit plates in which each valve unit is formed with a plurality oflayers 624, 626, 628. The layers may include axial passages, and thesepassages may be aligned along the axis of the inserted multi-lumen coreshafts to define multi-lumen receptacles, inflation headers, deflationheaders, and the like. Discrete microelectromechanical system (MEMS)valves may be electrically coupled to the processor and/or mounted to aplate layer using a flex circuit, which may optionally having O-ringsmounted or formed thereon to seal between adjacent valve unit plates.Channels may provide flow between the valve ports, headers, andmulti-lumen receptacles, and may be sealingly bonded between platelayers. Suitable MEMS valves may be available from DunAn Microstaq,Inc., of Texas., NanoSpace of Sweeden, Moog of California, or others.The plate layers may comprise polymers (particularly polymers which aresuitable for use at low temperatures (such as PTFE, FEP, PCTFE, or thelike), metal (such as aluminum, stainless steel, brass, alloys, anamorphous metal alloy such as a Liquidmetal™ alloy, or the like), glass,semiconductor materials, or the like, and may be mechanically machinedor laser-micromachined, 3D printed, or patterned usingstereolithography, but will preferable be molded. Alternative MEMS valvesystems may have the valve structure integrated into the channel platestructure, further reducing size and weight.

Referring now to FIGS. 19 and 20, a simplified exemplary C-channelstructural skeleton 630 (or portion or cross section of a skeleton) isshown in an axially extended configuration (in FIG. 19), and in anaxially contracted configuration (in FIG. 20). C-frame skeleton 630includes an axial series of C-channel members or frames 632 extendingbetween a proximal end 634 and a distal end 636, with each rigidC-channel including an axial wall 638, a proximal flange 640, and adistal flange 642 (generically referenced as flanges 640). The opposedmajor surfaces of the walls 644, 646 are oriented laterally, and theopposed major surfaces of the flanges 648, 650 are oriented axially (andmore specifically distally and proximally, respectively. The C-channelsalternate in orientation so that the frames are interlocked by theflanges. Hence, axially adjacent frames overlap, with the proximal anddistal surfaces 650, 648 of two adjacent frames defining an overlapoffset 652. The flanges also define additional offsets 654, with theseoffsets being measured between flanges of adjacent similarly orientedframes.

In the schematics of FIGS. 19 and 20, three balloons are disposed in thechannels of each C-frame 632. Although the balloons themselves may (ormay not) be structurally similar, the balloons are of two differentfunctional types: extension balloons 660 and contraction balloons 662.Both types of balloons are disposed axially between a proximallyoriented surface of a flange that is just distal of the balloon, and adistally oriented surface of a flange that is just proximal of theballoon. However, contraction balloons 662 are also sandwiched laterallybetween a first wall 638 of a first adjacent C-channel 632 and a secondwall of a second adjacent channel. In contrast, extension balloons 660have only a single wall on one lateral side; the opposite sides ofextension balloons 660 are not covered by the frame (though they willtypically be disposed within a flexible sheath or other components ofthe overall catheter system).

A comparison of C-frame skeleton 630 in the elongate configuration ofFIG. 19 to the skeleton in the short configuration of FIG. 20illustrates how selective inflation and deflation of the balloons can beused to induce axial extension and contraction. Note that the C-frames632 are shown laterally reversed from each other in these schematics. InFIG. 19, extension balloons 660 are being fully inflated, pushing theadjacent flange surfaces apart so as to increase the axial separationbetween the associated frames. As two contraction balloons 662 aredisposed in each C-channel with a single extension balloon, and as thesize of the channel will not significantly increase, the contractionballoons will often be allowed to deflate at least somewhat withexpansion of the extension balloons. Hence, offsets 654 will be urged toexpand, and contraction offsets 652 will be allowed to decrease. Incontrast, when skeleton 630 is to be driven toward the axiallycontracted configuration of FIG. 20, the contraction balloons 662 areinflated, thereby pushing the flanges of the overlapping frames axiallyapart to force contraction overlap 652 to increase and axially pull thelocal skeleton structure into a shorter configuration. To allow the twocontraction balloons 662 to expand within a particular C-channel, theexpansion balloons 660 can be allowed to deflate.

While the overall difference between C-frame skeleton 630 in thecontracted configuration and in the extended configuration issignificant (and such skeletons may find advantageous uses), it isworthwhile noting that the presence of one extension balloon and twocontraction balloons in a single C-channel may present disadvantages ascompared to other extension/contraction frame arrangements describedherein. In particular, the use of three balloons in one channel canlimit the total stroke or axial change in the associated offset thatsome of the balloons may be able to impose. Even if similar balloon/coreassemblies are used as extension and contraction balloons in athree-balloon wide C-channel, the two contraction balloons may only beused for about half of the stroke of the single extension balloon, asthe single extension stroke in the channel may not accommodate two fullcontractions strokes. Moreover, there are advantages to limiting thenumber of balloon/core assemblies used in a single articulated segment.

Note that whichever extension/contraction skeleton configuration isselected, the axial change in length of the skeleton that is inducedwhen a particular subset of balloons are inflated and deflated willoften be local, optionally both axially local (for example, so as tochange a length along a desired articulated segment without changinglengths of other axial segments) and—where the frames extend laterallyand/or circumferentially—laterally local (for example, so as to impose alateral bend by extending one lateral side of the skeleton withoutchanging an axial length of the other lateral side of the skeleton).Note also that use of the balloons in opposition will often involvecoordinated inflating and deflating of opposed balloons to provide amaximum change in length of the skeleton. There are significantadvantages to this arrangement, however, in that the ability toindependently control the pressure on the balloons positioned on eitherside of a flange (so as to constrain an axial position of that flange)allows the shape and the position or pose of the skeleton to bemodulated. If both balloons are inflated evenly at with relatively lowpressures (for example, at less that 10% of full inflation pressures),the flange may be urged to a middle position between the balloons, butcan move resiliently with light environmental forces by compressing thegas in the balloons, mimicking a low-spring force system. If bothballoons are evenly inflated but with higher pressures, the skeleton mayhave the same nominal or resting pose, but may then resist deformationfrom that nominal pose with a greater stiffness.

An alternative S-channel skeleton 670 is shown schematically incontracted and extended configurations in FIGS. 21A and 21B,respectively, which may have both an improved stroke efficiency (givinga greater percent change in axial skeleton length for an availableballoon stroke) and have fewer components than skeleton 632. S-skeleton670 has many of the components and interactions described aboveregarding C-frame skeleton 630, but is here formed of structuralS-channel members or frames 672. Each S-channel frame 672 has two walls644 and three flanges 640, the proximal wall of the frame having adistal flange that is integral with the proximal flange of the distalwall of that frame. Axially adjacent S-channels are again interlocked,and in this embodiment, each side of the S-channel frame has a channelthat receives one extension balloon 660 and one contraction balloon 662.This allows all extension balloons and all contraction balloons to takefull advantage of a common stroke. Moreover, while there are twoextension balloons for each contraction balloon, every other extensionballoon may optionally be omitted without altering the basicextension/contraction functionality (though the forces available forextension may be reduced). In other words, if the extension balloons660′ as marked with an X were omitted, the skeleton could remain fullyconstrained throughout the same nominal range of motion. Hence,S-channel frame 672 may optionally use three or just two sets of opposedballoons for a particular articulation segment.

Referring now to FIG. 22A, a modified C-frame skeleton 680 hascomponents that share aspects of both C-frame skeleton 630 and S-frameskeleton 670, and may offer advantages over both in at least someembodiments. Modified C skeleton 680 has two different generallyC-frames or members: a C-frame 682, and a bumper C-frame 684. C-frame682 and bumper frame 64 both have channels defined by walls 644 andflanges 648 with an axial width to accommodate two balloon assemblies,similar to the channels of the S-frames 672. Bumper frame 684 also has aprotrusion or nub 686 that extends from one flange axially into thechannel. The adjacent axial surfaces of these different frame shapesengage each other at the nub 686, allowing the frames to pivot relativeto each other and facilitating axial bending of the overall skeleton,particularly when using helical frame members.

Referring now to FIGS. 22B and 22C, a relationship between the schematicextension/retraction frame illustration of FIGS. 20A-22A and a firstexemplary three dimensional skeleton geometry can be understood. To forman axisymmetric ring-frame skeleton structure 690 from the schematicmodified C-frame skeleton 680 of FIG. 22B, the geometry of frame members682, 684 can be rotated about an axis 688, resulting in annular or ringframes 692, 694. These ring frames retain the wall and flange geometrydescribed above, but now with annular wall and flanges beinginterlocked. The annular C-frames 682, 684 were facing differentdirections in schematic skeleton 680, so that outer C-frame ring 692 hasan outer wall (sometimes being referred to as outer ring frame 692) anda channel that opens radially inwardly, while bumper C-frame ring 694has a channel that is open radially outwardly and an inner wall (so thatthis frame is sometimes referred to as the inner ring frame 694). Ringnub 696 remains on inner ring frame 694, but could alternatively beformed on the adjacent surface of the outer ring frame (or usingcorresponding features on both). Note that nub 696 may add more valuewhere the frame deforms with bending (for example, the frame deformationwith articulation of the helical frame structures described below) asthe deformation may involve twisting that causes differential angels ofthe adjacent flange faces. Hence, a non-deforming ring frame structuremight optionally omit the nub in some implementations.

Referring now to FIGS. 22C-22F, uniform axial extension and contractionof a segment of ring-frame skeleton 690 is performed largely asdescribed above. To push uniformly about the axis of the ring frames,three balloons are distributed evenly about the axis between the flanges(with centers separated by 120 degrees). The balloons are shown here asspheres for simplicity, and are again separated into extension balloons660 and contraction balloons 662. In the straight extended configurationof FIG. 22D, the extension balloons 660 of the segment are all fullyinflated, while the contraction balloons 662 are all fully deflated. Inan intermediate length configuration shown in FIG. 22E, both sets ofballoons 660, 662 are in an intermediate inflation configuration. In theshort configuration of FIG. 22F, contraction balloons 662 are all fullyinflated, while extension balloons 660 are deflated. Note that the stateof the balloons remains axisymmetrical, so that the lengths on alllateral sides of the ring frame skeleton 690 remain consistent and theaxis of the skeleton remains straight.

As can be understood with reference to FIGS. 22G and 22H, lateralbending or deflection of the axis of ring-frame skeleton 690 can beaccomplished by differential lateral inflation of subsets of theextension and contraction balloons. There are three balloons distributedabout the axis between each pair of articulated flanges, so that theextension balloons 660 are divided into three sets 660 i, 660 ii, and660 iii. Similarly, there are three sets of contraction balloons 662 i,662 ii, and 662 iii. The balloons of each set are aligned along the samelateral orientation from the axis. In some exemplary embodiments, eachset of extension balloons (extension balloons 660 i, extension balloons660 ii, and extension balloons 660 iii) along a particular segment iscoupled to an associated inflation fluid channel (for example, a channeli for extension balloons 660 i, a channel ii for extension balloons 660ii, and a channel iii for extension balloons 660 iii, the channels notshown here). Similarly, each set of contraction balloons 662 i, 662 ii,and 662 iii is coupled to an associated inflation channel (for example,channels iv, v, and vi, respectively) so that there are a total of 6lumens or channels per segment (providing three degrees of freedom andthree orientation-related stiffnesses). Other segments may have separatefluid channels to provide separate degrees of freedom, and alternativesegments may have fewer than 6 fluid channels. Regardless, byselectively deflating the extension balloons of a first lateralorientation 660 i and inflating the opposed contraction balloons 662 i,a first side of ring frame skeleton 690 can be shortened. By selectivelyinflating the extension balloons of the other orientations 660 ii, 660iii, and by selectively deflating the contraction balloons of thoseother orientations 662 ii, 662 iii, the laterally opposed portion ofring frame skeleton 690 can be locally extended, causing the axis of theskeleton to bend. By modulating the amount of elongation and contractiondistributed about the three opposed extension/contraction balloonorientations, the skeleton pose can be smoothly and continuously movedand controlled in three degrees of freedom.

Referring now to FIGS. 23A and 23B, as described above with reference toFIGS. 21A and 21B, while it is possible to include balloons between allthe separated flanges so as to maximize available extension forces andthe like, there may be advantages to foregoing kinematically redundantballoons in the system for compactness, simplicity, and cost. Towardthat end, ring frame skeletons having 1-for-1 opposed extension andcontraction balloons (660 i, 660 ii, and 660 iii; and 662 i, 662 ii, and662 iii) can provide the same degrees of freedom and range of motion asprovided by the segments of FIGS. 22G and 22H (including two transverseX-Y lateral bending degrees of freedom and an axial Z degree offreedom), and can also control stiffness, optionally differentiallymodulating stiffness of the skeleton in different orientations in 3Dspace. The total degrees of freedom of such a segment may appropriatelybe referenced as being 4-D (X, Y, Z, & S for Stiffness), with thestiffness degree of freedom optionally having 3 orientational components(so as to provide as many as 5-D or 6-D. Regardless, the 6 fluidchannels may be used to control 4 degrees of freedom of the segment.

As can be understood with reference to FIGS. 23C-23E and 23H, elongateflexible bodies having ring-frame skeletons 690′ with larger numbers ofinner and outer ring frames 692, 694 (along with associated largernumbers of extension and retraction balloons) will often provide agreater range of motion than those having fewer ring frames. Theelongation or Z axis range of motion that can be provided by balloonarticulation array may be expressed as a percentage of the overalllength of the structure, with larger percentage elongations providinggreater ranges of motion. The local changes in axial length that aballoon array may be able to produce along a segment having ring frames690, 690′ (or more generally having the extension contraction skeletonsystems described herein) may be in a range of from about 1 percent toabout 45 percent, typically being from about 2½ percent to about 25percent, more typically being from about 5 percent to about 20 percent,and in many cases being from about 7½ percent to about 17½ percent ofthe overall length of the skeleton. Hence, the longer axial segmentlength of ring frame skeleton 690′ will provide a greater axial range ofmotion between a contracted configuration (as shown in FIG. 23E) and anextended configuration (as shown in FIG. 23C), while still allowingcontrol throughout a range of intermediate axial length states (as shownin FIG. 23D).

As can be understood with reference to FIGS. 23A, 23B, 23D and 23H,setting the balloon pressures so as to axially contract one side of aring frame skeleton 690′ (having a relatively larger number of ringframes) and axially extend the other side laterally bends or deflectsthe axis of the skeleton through a considerable angle (as compared to aring frame skeleton having fewer ring frames), with each frame/frameinterface typically between 1 and 15 degrees of axial bend angle, moretypically being from about 2 to about 12 degrees, and often being fromabout 3 to about 8 degrees. A catheter or other articulated elongateflexible body having a ring frame skeleton may be bent with a radius ofcurvature (as measured at the axis of the body) of between 2 and 20times an outer diameter of the skeleton, more typically being from about2.25 to about 15 times, and most often being from about 2.4 to about 8times. While more extension and contraction balloons 660, 662 are usedto provide this range of motion, the extension and contraction balloonsubsets (660 i, 660 ii, and 660 iii; and 662 i, 662 ii, and 662 iii) maystill each be supplied by a single common fluid supply lumen. Forexample, 6 fluid supply channels may each be used to inflate and deflate16 balloons in the embodiment shown, with the balloons on a single lumenbeing extension balloons 660 i aligned along one lateral orientation.

As can be understood with reference to ring frame skeleton 690′ in thestraight configuration of FIG. 23D, in the continuously bentconfiguration of FIG. 23H, and in the combined straight and bentconfiguration of FIG. 23F, exemplary embodiments of the elongateskeleton 690′ and actuation array balloon structures described hereinmay be functionally separated into a plurality of axial segments 690 i,690 ii. Note that many or most of the skeleton components (includingframe members or axial series of frame members, and the like) andactuation array components (including the substrate and/or core, some orall of the fluid channels, the balloon outer tube or sheath material,and the like), along with many of the other structures of the elongateflexible body (such as the inner and outer sheaths, electricalconductors and/or optical conduits for diagnostic, therapeutic, sensing,navigation, valve control, and other functions) may extend continuouslyalong two or more axial segments with few or no differences betweenadjacent segments, and optionally without any separation in thefunctional capabilities between adjacent segments. For example, anarticulated body having a two-segment ring frame skeleton 690′ system asshown in FIG. 23H may have a continuous axial series of inner and outerring frames 692, 694 that extends across the interface between thejoints such that the two segments can be bent in coordination with aconstant bend radius by directing similar inflation fluid quantities andpressures along the fluid supply channels associated with the twoseparate segments. As can be understood with reference to FIG. 23G,other than differing articulation states of the segments, there mayoptionally be few or no visible indications of where one segment endsand another begins.

Despite having many shared components (and a very simple and relativelycontinuous overall structure), functionally separating an elongateskeleton into segments provides tremendous flexibility and adaptabilityto the overall articulation system. Similar bend radii may optionally beprovided with differing stiffnesses by applying appropriately differingpressures to the opposed balloons 660, 662 of two (or more) segments 690i, 690 ii. Moreover, as can be understood with reference to FIG. 23F,two (or more) different desired bend radii, and/or two different lateralbend orientations and/or two different axial segments lengths can beprovided by applying differing inflation fluid supply pressures to theopposed contraction/extension balloon sets 660 i, 660 ii, 660 iii, 662i, 662 ii, 662 iii of the segments. Note that the work spaces ofsingle-segment and two-segment systems may overlap so that both types ofsystems may be able to place an end effector or tool at a desiredposition in 3D space (or even throughout a desired range of locations),but multiple-segment systems will often be able to achieve additionaldegrees of freedom, such as allowing the end effector or tool to beoriented in one or more rotational degrees of freedom in 6D space. Asshown in FIG. 23J, articulated systems having more than two segmentsoffer still more flexibility, with this embodiment of ring frameskeleton 690′ having 4 functional segments 690 a, 690 b, 690 c, and 690d. Note that still further design alternatives may be used to increasefunctionality and cost/complexity of the system for a desired workspace,such as having segments of differing length (such as providing arelatively short distal segment 690 a supported by a longer segmenthaving the combined lengths of 690 b, 690 c, and 690 d. While many ofthe multi-segment embodiments have been shown and described withreference to to planar configurations of the segments where all thesegments lie in a single plane and are either straight or in a fullybent configuration, it should also be fully understood that theplurality of segments 690 i, 690 ii, etc., may bend along differingplanes and with differing bend radii, differing axial elongation states,and/or differing stiffness states, as can be understood with referenceto FIG. 23I.

Catheters and other elongate flexible articulated structures having ringframe skeletons as described above with reference to FIGS. 22C-23Iprovide tremendous advantages in flexibility and simplicity over knownarticulation systems, particularly for providing large numbers ofdegrees of freedom and when coupled with any of the fluid supply systemsdescribed herein. Suitable ring frames may be formed of polymers (suchas nylons, urethanes, PEBAX, PEEK, HDPE, UHDPE, or the like) or metals(such as aluminum, stainless steel, brass, silver, alloys, or the like),optionally using 3D printing, injection molding, laser welding, adhesivebonding, or the like. Articulation balloon substrate structures mayinitially be fabricated and the balloon arrays assembled with thesubstrates in a planar configuration as described above, with the arraysthen being assembled with and/or mounted on the skeletons, optionallywith the substrates being adhesively bonded to the radially innersurfaces of the inner rings and/or to the radially outer surfaces of theouter rings, and with helical or serpentine axial sections of thesubstrate bridging between ring frames. While extension and retractionballoons 660, 662 associated with the ring frame embodiments are shownas spherical herein, using circumferentially elongate (and optionallybent) balloons may increase an area of the balloon/skeleton interface,and thereby enhance axial contraction and extension forces. A hugevariety of modifications might also be made to the general ring-frameskeletal arrangement and the associated balloon arrays. For example,rather than circumferentially separating the balloons into three lateralorientations, alternative embodiments may have four lateral orientations(+X, −X, +Y, and −Y) so that four sets of contraction balloons aremounted to the frame in opposition to four sets of extension balloons.Regardless, while ring-frame skeletons have lots of capability andflexibility and are relatively geometrically simple so that theirfunctionality is relatively easy to understand, alternativeextension/contraction articulation systems having helical skeletonmembers (as described below) may be more easily fabricated and/or moreeasily assembled with articulation balloon array components,particularly when using the advantageous helical multi-lumen coresubstrates and continuous balloon tube structures described above.

First reviewing components of an exemplary helical framecontraction/expansion articulation system, FIGS. 24A-24E illustrateactuation balloon array components and their use in a helical balloonassembly. FIGS. 24F and 24G illustrate exemplary outer and inner helicalframe members. After reviewing these components, the structure and useof exemplary helical contraction/expansion articulation systems(sometimes referred to herein as helical push/pull systems) can beunderstood with reference to FIGS. 25 and 26.

Referring now to FIGS. 24A and 24B, an exemplary multi-lumen conduit orballoon assembly core shaft has a structure similar to that of the coredescribed above with reference to FIGS. 14 and 15. Core 702 has aproximal end 704 and a distal end 706 with a multi-lumen body 708extending therebetween. A plurality of lumens 710 a, 710 b, 710 c, . . .extend between the proximal and distal ends. The number of lumensincluded in a single core 702 may vary between 3 and 30, with exemplaryembodiments have 3, 7 (of which one is a central lumen), 10 (including 1central), 13 (including 1 central), 17 (one being central), or the like.The multi-lumen core will often be round but may alternatively have anelliptical or other elongate cross-section as described above. Whenround, core 702 may have a diameter 712 in a range from about 0.010″ toabout 1″, more typically being in a range from about 0.020″ to about0.250″, and ideally being in a range from about 0.025″ to about 0.100″for use in catheters. Each lumen will typically have a diameter 714 in arange from about 0.0005″ to about 0.05″, more preferably having adiameter in a range from about 0.001″ to about 0.020″, and ideallyhaving a diameter in a range from about 0.0015″ to about 0.010″. Thecore shafts will typically comprise extruded polymer such as a nylon,urethane, PEBAX, PEEK, PET, other polymers identified above, or thelike, and the extrusion will often provide a wall thickness surroundingeach lumen of more than about 0.0015″, often being about 0.003″ or more.The exemplary extruded core shown has an OD of about 0.0276″″, and 7lumens of about 0.004″ each, with each lumen surrounded by at least0.004″ of the extruded nylon core material.

Referring still to FIGS. 24A and 24B, the lumens of core 702 may haveradial balloon/lumen ports 716 a, 716 b, 716 c, . . . , with each portcomprising one or more holes formed through the wall of core 702 andinto an associated lumen 710 a, 710 b, 710 c, . . . respectively. Theports are here shown as a group of 5 holes, but may be formed using 1 ormore holes, with the holes typically being round but optionally beingaxially elongate and/or shaped so as to reduce pressure drop of fluidflow therethrough. In other embodiments (and particularly those having aplurality of balloons supplied with inflation fluid by a single lumen),having a significant pressure drop between the lumen and the balloon mayhelp even the inflation state of balloons, so that a total cross sectionof each port may optionally be smaller than a cross-section of the lumen(and/or by limiting the ports to one or two round lumens). Typical portsmay be formed using 1 to 10 holes having diameters that are between 10%of a diameter of the associated lumen and 150% of the diameter of thelumen, often being from 25% to 100%, and in many cases having diametersof between 0.001″ and 0.050″. Where more than one hole is included in aport they will generally be grouped together within a span that isshorter than a length of the balloons, as each port will be containedwithin an associated balloon. Spacing between the ports will correspondto a spacing between balloons to facilitate sealing of each balloon fromthe axially adjacent balloons.

Regarding which lumens open to which ports, the ports along a distalportion of the core shaft will often be formed in sets, with each setbeing configured to provide fluid flow to and from an associated set ofballoons that will be distributed along the loops of the core (once thecore is bent to a helical configuration) for a particular articulatedsegment of the articulated flexible body. When the number of lumens inthe core is sufficient, there will often be separate sets of ports fordifferent segments of the articulated device. The ports of each set willoften form a periodic pattern along the axis of the multi-lumen core702, so that the ports provide fluid communication into M differentlumens (M being the number of different balloon orientations that are tobe distributed about the articulated device axis, often being 3 or 4,i.e., lumen 710 a, lumen 710 b, and lumen 710 c) and the patternrepeating N times (N often being the number of contraction balloonsalong each orientation of a segment). Hence, the multi-lumen coreconduit can function as a substrate that supports the balloons, and thatdefines the balloon array locations and associated fluid supply networksdescribed above. Separate multi-lumen cores 702 and associated balloonarrays may be provided for contraction and expansion balloons.

As one example, a port pattern might be desired that includes a 3×5contraction balloon array for a particular segment of a catheter. Thisset of ports might be suitable when the segment is to have three lateralballoon orientations (M=3) and 5 contraction balloons aligned along eachlateral orientation (N=5). In this example, the distal-most port 716 aof the set may be formed through the outer surface of the core into afirst lumen 710 a, the next proximal port 716 b to lumen 710 b, the nextport 716 c to lumen 710 c, so that the first 3 (M) balloons define an“a, b, c” pattern that will open into the three balloons that willeventually be on the distal-most helical loop of the set. The samepattern may be repeated 5 times (for example: a, b, c, a, b, c, a, b, c,a, b, c, a, b, c) for the 5 loops of the helical coil that will supportall 15 contraction balloons of a segment to the fluid supply system suchthat the 5 contraction balloons along each orientation of the segmentare in fluid communication with a common supply lumen. Where the segmentwill include expansion balloons mounted 1-to-1 in opposition to thecontraction balloons, a separate multi-lumen core and associated balloonmay have a similar port set; where the segment will include 2 expansionballoons mounted in opposition for each contraction balloon, twoseparate multi-lumen cores and may be provided, each having a similarport set.

If the same multi-lumen core supplies fluid to (and supports balloonsof) another independent segment, another set of ports may be providedaxially adjacent to the first pattern, with the ports of the second setbeing formed into an M′×N′ pattern that open into different lumens ofthe helical coil (for example, where M′=3 and N′=5: d, e, f, d, e, f, d,e, f, d, e, f, d, e, f), and so on for any additional segments. Notethat the number of circumferential balloon orientations (M) will oftenbe the same for different segments using a single core, but may bedifferent in some cases. When M differs between different segments ofthe same core, the spacing between ports (and associated balloonsmounted to the core) may also change. The number of axially alignedcontraction balloons may also be different for different segments of thesame helical core, but will often be the same. Note also that all theballoons (and associated fluid lumens) for a particular segment that areon a particular multi-lumen core will typically be either only extensionor only contraction balloons (as the extension and contraction balloonarrays are disposed in helical spaces that may be at least partiallyseparated by the preferred helical frame structures described below). Asingle, simple pattern of ports may be disposed near the proximal end ofcore shaft 702 to interface each lumen with an associated valve plate ofthe manifold, the ports here being sized to minimized pressure drop andthe port-port spacing corresponding to the valve plate thickness.Regardless, the exemplary core shown has distal ports formed usinggroups of 5 holes (each having a diameter of 0.006″, centerline spacingwithin the group being 0.012″), with the groups being separated axiallyby about 0.103″.

Referring still to FIGS. 24A and 24B, an exemplary laser drillingpattern for forming ports appropriate for an articulated two distalsegments, each having a 3×4 balloon array, may be summarized in tableform as shown in Table 1:

TABLE 1 Drill to Lumen #s _\ Theta 1 Theta 2 Theta 3 Segment 1, 1 2 3 N1N2 1 2 3 N3 1 2 3 N4 1 2 3 Segment 2, 4 5 6 N1 N2 4 5 6 N3 4 5 6 N4 4 56Theta 1, Theta 2, and Theta 3 here indicate the three lateral bendingorientations, and as M=3, the balloons will typically have centerlinesseparated by about 120 degrees once the balloon/shaft assembly iscoiled. Hence, the centerline spacing between the ports along thestraight shaft (prior to coiling) will typically correspond to a helicalpath length having about a 120 degree arc angle of the final articulatedstructure, both within a particular N subset and between adjacent Nsubsets of a nearby segment. However, the alignment of eachcircumferential subset along a lateral bending axis does not necessarilymean that adjacent balloons are separated by precisely 120 degrees, orthat the N balloons of a subset are aligned exactly parallel to the axiswhen the segment is in all configurations. For example, there may besome unwinding of the helical core associated with axial elongation, andthere may be benefits to having the balloons along a particular bendingorientation trending slightly circumferentially around the axis (whengoing from balloon to balloon of a lateral bending subset) so thatlateral bends are closer to being planer in more segment states. Theseparation between balloons may remain consistent between segments, ormay be somewhat longer to accommodate affixation of the balloon/shaftassembly to frames and inner and outer sheaths. Drill patterns for theproximal end may be somewhat simpler, as a single port may be drilled toprovide fluid communication between each lumen and an associated valveplate module of the manifold assembly, an example of which is shown inTable 2:

TABLE 2 Drill to Lumen #s Plate 1 1 Plate 2 2 Plate 3 3 Plate 4 4 Plate5 5 Plate 6 6 Plate 7 Plate 8Note that this tabular data provides a correlation between valves of aplate and subsets of articulation balloons, and thus of the kinematicsof the system. Hence, the system processor will often have access tothis or related data when an articulated structure is coupled with themanifold, preferably on a plug-and-play basis. Similar (though possiblydifferent) drill pattern data may correlate the drill patterns of othermulti-lumen cores with their associated valves and kinematics. Note thatnot all valves and valve plates need be used; where a particulararticulated device has fewer lumens or balloon subsets than the manifoldis capable of controlling, there may well be unused plates and valves.

Referring now to FIGS. 24C and 24D, a continuous tube of flexibleballoon wall material 718 may be formed by periodically varying adiameter of tube wall material to form a series of balloon shapes 720separated by smaller profile sealing zones 722. Balloon tube 718 mayinclude between about 9 and about 290 regularly spaced balloon shapes720, with the sealing zones typically having an inner diameter that isabout equal to the outer diameters of the multi-lumen helical coreshafts 702 described above. In some embodiments, the inner diameters ofthe sealing zones may be significantly larger than the outer diametersof the associated cores when the balloon tube is formed, and thediameters of the sealing zones may be decreased (such as by heatshrinking or axially pull-forming) before or during assembly of theballoon tube and core shaft. The sealing zone may have a length ofbetween about 0.025″ and about 0.500″, often being between about 0.050″and about 0.250″. Decreasing the length of the sealing zone allows thelength of the balloon to be increased for a given catheter size so as toprovide larger balloon/frame engagement interfaces (and thus greaterarticulation forces), while longer sealing zones may facilitate assemblyand sealing between balloons so as to avoid cross-talk betweenarticulation channels.

Referring still to FIGS. 24C and 24D, the balloon shapes 720 of theballoon tube 718 may have diameters that are larger than the diametersof the sealing zones by between about 10% and about 200%, more typicallybeing larger by an amount in a range from about 20% to about 120%, andoften being from about 40% to about 75%. The thickness of balloon tube718 will often vary axially with the varying local diameter of the tube,the locally large diameter portions forming the balloon shapesoptionally being in a range from about 0.00008′ (or about 2 microns) toabout 0.005″, typically being from about 0.001″ and about 0.003″.Balloon tube 718 may initially be formed with a constant diameter andthickness, and the diameter may be locally expanded (by blow forming, byvacuum forming, by a combination of both blow forming and vacuumforming, or by otherwise processing the tube material along the balloonshapes 720), and/or the diameter of the balloon tube may be locallydecreased (by heat shrinking, by axial pull-forming, by a combination ofboth heat shrinking and pull forming, or by otherwise processing thetube material along the sealing zones), with the tube material oftenbeing processed so as to both locally expand the diameter along thedesired balloon shapes and to locally contract the diameter along thesealing zones. Particularly advantageous techniques for forming balloontubes may include the use of extruded polymer tubing corrugators,including the vertical small bore corrugators commercially availablefrom Unicore, Corma, Fraenkische, and others. Suitable custom molds forsuch pipe corrugators may be commercially available from GlobalMed,Custom Pipe, Fraenkische, and others. Still more advanced fabricationtechniques may allow blow or vacuum corrugation using a robotic shuttlecorrugator and custom molds, particularly when it is desirable to changea size or spacing of balloons along a continuous tube. It should benoted that while a single continuous balloon tube is shown, a pluralityof balloon tubes (each having a plurality (or in some cases, at leastone) balloon shape) can be sealingly mounted onto a single core.Regardless, the sealing zones will often have a material thickness thatis greater than that of the balloon shapes.

The balloon shapes 720 of the balloon tube 718 may each have arelatively simple cylindrical center section prior to assembly as shown.The tapers between the balloon center sections and the sealing zones cantake any of a variety of shapes. The tapers may, for example, be roughlyconical, rounded, or squared, and will preferably be relatively short soas to allow greater balloon/frame engagement for a given landing zonelength. More complex embodiments may also be provided, including formingthe balloon shapes with curved cylindrical center sections, optionallywhile corrugating or undulating the surfaces of the tapers so that theballoon tube overall remains relatively straight. The lengths of eachcenter section is typically sufficient to define an arc-angle of from 5to 180 degrees about the axis of the desired balloon assembly helix,more typically being from about 10 to about 50 degrees, the lengths ofthe center sections often being in a range from about 0.010″ to about0.400″ for medical applications, more typically being from about 0.020″to about 0.150″, and many times being in a range from about 0.025″ toabout 0.100″. The exemplary balloon shapes may have an outer diameter ofabout 0.051″ over a total balloon length (including the tapers) of about0.059″

As can be understood with reference to FIGS. 24C, 24D, and 24E, balloontube 718 may be sealingly affixed to core 702, and the core/balloon tubeassembly may then be formed into a desired helical shape. The balloontube may be sealed over the helical core using adhesive (such as any ofthose described above, often including UV-cured adhesives) thermalbonding, laser bonding, die bonding, and/or the like. Sealing of theballoons may also benefit from a compression structure disposed over theballoon material to help maintain tube/core engagement when the balloonsare inflated. Suitable compression structures or techniques may includeshort sections of heat-shrink materials (such as PET) shrunk onto thesealing zones, high-strength filament windings wrapped circumferentiallyaround the sealing zones and adhesively bonded, swaging of metallic ringstructures similar to marker bands over the sealing zones, small borecrimp clamps over the sealing zones, heat-shrinking and/or pull formingthe balloon tube onto the core, or the like. Any two or more of thesemay also be combined, for example, with the balloon tube beingadhesively bonded to the core tube by injecting adhesive into theballoon tube around the sealing zone, heat shrinking the balloon tubeand a surrounding PET sleeve over the sealing zone, and then swaging ametallic marker band over the sealing PET sleeve (so that the sleeveprovides strain relief). Regardless, ports 716 will preferably bedisposed within corresponding balloon shapes 720 and will remain openafter the balloon/core assembly 730 is sealed together in the straightconfiguration shown in FIG. 24D. Shape setting of the balloon/coreassembly from the straight configuration to the helically curvedconfiguration of FIG. 24E can be performed by wrapping the assemblyaround and/or within a mandrel and heating the wrapped assembly. Helicalchannels may be included in the mandrel, which may also have discreteballoon receptacles or features to help ensure alignment of sets ofballoons along the desired lateral balloon axes. Regardless, shapesetting of the core/balloon assembly can help set the M differentlateral orientations of the balloons, so that the balloons of each set720 i, 720 ii, 720 iii are aligned.

Referring to FIG. 24E-2, an alternative balloon tube 718′ has aplurality of pre-curved balloon shapes 720′ coupled together by sealingzones 722 to facilitate forming the balloon/core assembly in a helicalconfiguration. The overall configuration of alternative balloon tube718′ is straight, and it may be beneficial to provide corrugatedtransitions 725 between pre-curved balloon shapes 720′ and sealing zones722. Corrugated transitions 725 may have a form analogous to that of acorrugated straw along an outer radial portion of the helix, and theballoon shapes may optionally have corrugations along this outer portioninstead of or in addition to the pre-curvature shown schematically here.The balloon shapes, transitions, and sealing zones may be formed by blowmolding within machined or printed tooling using medical balloon blowingtechniques, by blow molding with the moving tooling of a corrugationsystem, or the like.

As noted above, multilumen core or shaft 702 defines an axial series ofloops 721 i, 721 ii, 721 iii, . . . and having a plurality of lumens710. A plurality of balloons 720 is distributed along the loops 721,each balloon having a balloon wall extending around the shaft. Aplurality of ports opens into the shaft, each port 716 providing fluidcommunication between an associated balloon 720 and an associated lumen710. The balloons will often be configured so that inflation of theballoons will, in use, alter a bending state of the articulatable body.Optionally, a first subset of the balloons 723 i is distributed along afirst loop 721 i and a second subset of the balloons 723 ii isdistributed along a second loop 721 ii; a plurality of additionalsubsets 723 iii, . . . may be distributed along other loops 721 iii, . .. . In those or other embodiments, a third subset of the balloons 720 ican be offset from the axis and aligned along a first lateralorientation, and a fourth subset of the balloons 720 ii can be offsetfrom the axis and aligned along a second lateral orientation offset fromthe axis and from the first lateral orientation. The ports 716 aassociated with the third subset of balloons 720 i may be in fluidcommunication with a first lumen 710 a of the shaft 702, and the ports716 b associated with the fourth subset of balloons 720 ii may be influid communication with a second lumen 710 b of the shaft 702. Thethird and fourth subsets 720 i, 720 ii will often include balloons ofthe first, second, and other subsets 721 i, 721 ii . . . , and yetanother or fifth subset 723 iii of the balloons 720 can be offset fromthe axis and aligned along a third lateral orientation offset from thefirst and second lateral orientations. The balloons typically define anM×N array, with M lateral subsets of the balloons 720 i, 720 ii, 720iii, being distributed circumferentially about the axis, each of the Mlateral subsets including N balloons aligned along an associated lateralorientation. For example, M may be three or four, so that there arethree or four lateral subsets of balloons 720 i, 720 ii, 720 iii . . .distributed about the axis of the articulatable body (the centers of thesubsets optionally being separated by 120 or 90 degrees). The ports 716associated with the balloons 720 of each of the M lateral subsets mayprovide fluid communication between N balloons and an associated lumen710, so that each of the lateral orientations is associated with (oftenbeing inflated and/or deflated via) a particular lumen 710 a, 710 b, 710c of the shaft.

Referring to FIG. 24E-3, a detail for an exemplary seal between sealingzone 722 of balloon tube 718 and an outer surface of multi-lumen core702 is illustrated. In some embodiments, bonding 711 of balloon tube 718to core 702 employs adhesives, thermal bonding, laser bonding, or thelike, and is sufficient to inhibit fluid flow between adjacent balloons.Optionally, a band of radially compressive material 713 can be disposedover the balloon tube and core to help maintain sealing engagement whenone or both of the adjacent balloons are inflated. Suitable bands maycomprise metals that are crimped or swaged onto the assembly, with thebands optionally comprise thin tubular marker bands-like structures, andmay optionally comprise stainless steel, silver, gold, platinum, or thelike. Alternative compressive bands may comprise a flexible filament ofa polymer such as nylon, polyester, spectra, or the like, and may bewound over the balloon tube and core and adhesively bonded. Stillfurther alternative compressive bands may comprise a micro-crimp clamp,or the like. A strain-relief tube (optionally comprising PET or thelike) may optionally be provided between band 713 and balloon tube 718to inhibit damage along the edge of the band, and/or the band may beflared radially outwardly at the ends. Preferably, the band will becompressed onto the balloon so that at least the axial surfaces of theband (relative to the coiled balloon/core assembly) will be recessed tonear or even below the adjacent balloon tube without occluding thelumens of the core, analogous to when a standard marker band is crimpedonto a standard catheter tubing.

Referring now to FIGS. 24F and 24G, exemplary inner and outer helicalC-channel frames, 732 and 734 respectively, can be seen. Inner helicalframe 732 and outer helical frame 734 incorporate the modified C-channelframe 680 of FIG. 22A, but with the C-channels defined by axiallycontinuous helical walls 736 with flanges 740 along their proximal anddistal helical edges. The helical flanges are axially engaged by opposedballoons and allow inflation of the balloons to locally axially contractand/or extend the skeleton and catheter (or other articulatable body) ina manner that is analogous to the annular flanges of the ring framesdescribed above. An optional helical nub 742 protrudes axially into thechannel of inner ring frame 734 to allow the frames to pivot againsteach other along a flange/flange engagement, so that the nub couldinstead be included on the flange of the outer frame or on both (or maycomprise a separate structure that is axially sandwiched between theflanges of the two frames). Alternative embodiments may forego such apivotal structure altogether.

Referring now to FIGS. 25A-25D, a segment of an exemplary flexibleextension/contraction helical frame articulation structure 750(sometimes referred to herein as a push/pull helical structure)incorporates the components of FIGS. 24A-24G, and provides thefunctionality of the annular extension/contraction frame embodiments ofFIGS. 22B-22I. Push/pull structure includes a skeleton defined by innerand outer helical frames 732, 734, and also includes three balloon/coreassemblies 730 a, 730 b, and 730 c, respectively. Each balloon/coreassembly includes a set of balloons at three lateral orientations, 720i, 720 ii, and 720 iii. Balloon/core assembly 730 b extends along ahelical space that is axially between a flange of the inner frame and aflange of the outer frame, and that is radially between a wall of theinner frame and a wall of the outer frame, so that the frames overlapalong this balloon/core assembly. Hence, when balloons 720 ofballoon/core assembly 730 inflate, they push the adjacent flanges apartand increase the overlap of the frames, inducing axial contraction ofthe skeleton, such that the balloons of this assembly function ascontraction balloons. In contrast, balloon/core assemblies 730 a and 730c are radially adjacent to only inner frame 732 (in the case of assembly730 a) or outer frame 734 (in the case of assembly 730 b). Expansion ofthe balloons 720 of assemblies 730 a, 730 c pushes axially againstframes so as to decrease the overlap of the frames, and acts inopposition to the inflation of balloons 720 of assembly 730 b. Hence,balloons 720 of assemblies 730 a, 730 c function as extension balloons.

Referring now to FIGS. 25A-25C, when all the contraction balloons 720 ofassembly 730 b are inflated and all the extension balloons of assemblies730 a, 730 c are deflated, the push/pull structure 750 is in a straightshort configuration as shown in FIG. 25A. Even partial inflation of theextension balloons and even partial deflation of the contractionballoons articulates push/pull structure 750 to a straight intermediatelength configuration, and full inflation of all extension balloons ofassemblies 730 a, 730 c (along with deflation of the contractionballoons) fully axially elongates the structure. As with the ringpush/pull frames, inflating contraction balloons 720 ii along onelateral orientation of assembly 730 b (with corresponding deflation ofthe extension balloons 720 ii of assemblies 730 a, 730 b) locallydecreases the axial length of the skeleton along that side, whileselective deflation of contraction balloons 720 i of assembly 730 b(with corresponding inflation of extension balloons 720 i of assemblies730 a and 730 c) locally increases the length of the skeleton, resultingin the fully laterally bent configuration of FIG. 25E. Note thatextension and contraction balloons along the 720 iii orientation may beinflated and deflated with the extension and contraction orientationballoons of orientation 720 ii so as to keep the curvature in the planeof the drawing as shown. Stiffness of the structure may be modulateduniformly or locally (with axial and/or orientation variations) asdescribed above regarding the ring frame embodiments. Similarly, thenumber of extension and contraction balloons along each orientation(which will often be associated with the number of loops of assemblies730 a, 730 b, etc) may be determined to provide the desired range ofmotion, resolution, and response. As described with reference to thepush/pull ring frame embodiments, the overall articulated portion of thestructure will often be separated into a plurality of independentlycontrollable segments.

Referring now to FIG. 25F, push/pull structure 750 will often include anouter flexible sheath 752 and an inner flexible sheath 754. Sheaths 752,754 may be sealed together at a distal seal 756 distal of the inflationlumens and balloons of assemblies 730, and one or more proximal seal(not shown) may be provided proximal of the balloons and/or near aproximal end of the catheter structure, so as to provide a sealed volumesurrounding the articulation balloons. A vacuum can be applied to thissealed volume, and can be monitored to verify that no leaks are presentin the balloons or inflation lumen system within a patient body.

Referring now to FIGS. 26A and 26B, an alternative push/pull structureomits one of the two extension balloon assemblies 730 a, 730 c, and usesa 1-to-1 extension/contraction balloon opposition arrangement asdescribed above with reference to FIGS. 23A and 23B. Note that thisembodiment retains balloon assembly 730 c that is radially adjacent toouter frame 734 (so that no balloons are visible even with the sheathremoved). Alternative embodiments may retain assembly 730 a and foregoassembly 730 c (so that balloons could be seen through a clear sheath,for example).

Referring now to FIG. 27, short segments of alternative core structuresare shown for comparison. Core shaft 702 has an outer diameter of about0.028″ and 7 lumens, with 6 peripheral lumens having an inner diameterof about 0.004″ readily available for formation associated ports and usein transmitting inflation fluid to and from balloons. A central lumenmight be used, for example, in monitoring of the vacuum system to verifyintegrity of the system. Core shaft 702 can be used, for example, in a14-15 Fr catheter system having two segments that are each capable ofproviding up to 120 degrees of bending (or alternatively more or lessdepending on the number of balloons ganged together on each channel),with such a system optionally capable of providing a bend radiussufficient for to fit a 180 degree bend of the catheter within a spaceof 3 inches or less, ideally within 2½ inches or less, and in some caseswithin 2 inches or less. Such a system may be beneficial for structuralheart therapies, for example, and particularly for mitral valvedelivery, positioning, and/or implantation.

Referring still to FIG. 27, other therapies may benefit from smallercatheter profiles, and do not need the bending forces available from a15 Fr catheter. Electrophysilogy therapies such as AFib ablation fromwithin an atrium of the heart may be good examples of therapies whichwould benefit from the degrees of freedom that can be provided in smallstructures using the systems described herein. Scaling the 15 Fr systemdown for a 7-8 Fr ablation catheter might make use of a directly scaledcore 762 having half the overall outer diameter and half the lumen innerdiameter of core 702, as the pressure-containing stresses in thematerial would scale with the lumen diameters. However, there may becost benefits to maintaining minimum lumen wall thicknesses that areabove 0.002″, preferably at or above 0.0025″, and ideally at or aboveabout 0.003″. Toward that end, and to provide 6 contraction or extensionlumens for two 3D push/pull segments along a common helical core alongwith a desirably small bend radius, it may be beneficial to use radiallyelongate core 764 having a 6 lumens that are all surrounded by at least0.003″ of material. Core 764 has an axial height of half of core 702 anda radial width of that is less than half the balloon diameter of the14-15 Fr system. There may be benefits to having the radial (elongate)dimension of the cross-section being less than the inflated innerdiameter of the balloons mounted thereon, to inhibit trapping ofinflation fluid on one axial side of the balloon (away from theinflation port).

Still further advantages may be provided by applying the smaller lumenand wall thickness dimensions of 7 Fr core 762 to a 15 Fr catheter coresize, as it results in the 12 inflation lumen core 766. The large13^(th) lumen of this embodiment may help enhance flexibility of thesegments, and can again be used to monitor system integrity using avacuum system. The 12 lumens may allow, for example, a continuouspush/pull structure to have 4 independently controllable 3D shape (4Dshape+stiffness) segments. A 16 inflation lumen core 768 combines thesmaller lumen and wall thickness with a radially elongate cross-section,allowing 5 independently controllable 3D segments. It should beunderstood that still further numbers of lumens at smaller profiles arepossible using known and relatively low cost multilumen extrusiontechniques.

It should be understood that still further alternative embodiments maytake advantage of the beneficial components and assemblies describedherein. For example, as can be understood from the disclosure aboveregarding many of the flexible structures of FIGS. 3-12, inflation of aballoon may be resiliently opposed by a helical spring or other biasingstructure so that the spring deflates the balloon and urges a flexiblebody back toward a pre-balloon-inflation state when the inflation fluidis released from the balloon. Rather than relying on 6 dedicated opposedexpansion and contraction balloon channels for each segment (providingindependent contraction and expansion along each lateral orientation) inthe push/pull ring frame and push/pull helical frame embodimentsdescribed above, two or more of the channels (from the same segments orfrom different segments) may be grouped together to act as a commonbaising structure or fluid spring. As an example, all the contractionballoons along two adjacent segments might open to a single lumen thatis inflated to less than full pressure. Modulating pressure to thedifferent sets of extension balloons may still allow the extensionballoons to articulate each segment with three independent degrees offreedom, as the grouped contraction balloons could selectively beoverpowered by the extension balloons (like the coil springs) or may beallowed to deflate the extension balloons. In some embodiments, ratherthan relying on partial pressure of extension or contraction balloons,an elastomeric material may be mounted over the core of some or all ofthe extension or contraction balloons of a segment so as to passivelyoppose a set of the balloons.

Referring now to FIGS. 28A-28D, an alternative proximal interface 830 ofthe catheter can be understood, along with how it can be mated to analternative receptacle 832 of an alternative modular manifold 834.Proximal interface 830 provides sealed communication between axiallyseparated ports of up to three multi-lumen shafts 836, with the ports ofthe multi-lumen shafts being sealed by axially compressing O-rings 838or other deformable sealing bodies interleaved between more rigidinterface members 840. Threaded compression members 842 maintain axialsealing compression between a proximal-most interface member and adistal-most interface member. Posts 844 of interface members 840 extendlaterally and parallel to each other. Each interface member 840 includesa post 844 for each multi-lumen shaft, and the number of interfacemembers included in proximal interface 830 is the same as the number ofindependently used lumens in each multi-lumen shaft, so that the postsform an array with the total number of posts being equal to the totalnumber of independent multi-lumen channels in the articulated structure.Lumens extend radially from the ports of the multi-lumen shaft, throughthe posts 844, and to an interface port surrounded by a cap ofdeformable seal material.

Referring to FIG. 28D, receptacle 832 of manifold assembly 834 has aseries of indentations that correspond with posts 844 of proximalinterface 830. The indentations have surfaces that correspond to theposts and seal to the deformable caps with the interface ports each insealed fluid communication with an associated channel of an associatedplate module. In this embodiment, the receptacle surfaces of each platemodules are on a receptacle member 848. The receptacle members supportplate layers with channels formed between the layers, with MEMS valvesand pressure sensors mounted to the plates as described above. Here,however, the plates of adjacent plate modules may not be in directplate-plate contact, so that the supply and exhaust flows may extendaxially through the receptacle members, through the proximal interface,or through another structure of the manifold assembly. As noted above,alternative embodiments may have plates that are in direct contact, withany housings for valves, pressure sensors, and the like formed as voidsbetween layers, and with inflation and/or deflation fluid transmitteddirectly between plate modules through seals (such as O-rings,formed-in-place seals, gasket material affixed to flex circuitstructures, or the like).

Referring now to FIGS. 29A-29E, an alternative balloon-articulatedstructure 850 having a single multi-lumen core may be particularly wellsuited for smaller profile applications, such as for microcathetershaving sizes down to 2 or 3 Fr, guidewires, or the like. Articulatedstructure 850 generally has a proximal end 852 and a distal end 854 andmay define an axis therebetween. A frame 856 of the structure is shownby itself in FIG. 29C and is generally tubular, having a series of loops858 interconnected by axial struts 860. Two struts may be providedbetween each pair of adjacent loops, with those two struts beingcircumferentially offset by about 180 degrees; axially adjacent strutsbetween nearby loop pairs may be offset by about 90 degrees,facilitating lateral bending of the frame in orthogonal lateral bendingorientations. As will be understood from many of the prior framestructures described herein, apposed surface region pairs between loops858 will move closer together and/or farther apart with lateral bendingof frame 850, so that a balloon can be used to control the offsetsbetween these regions and thereby the bending state of the frame.

A multi-lumen core 862 is shown by itself in FIG. 29B, and extendsaxially within the lumen of frame 856 when used (as shown in FIG. 29D).Core 862 includes a plurality of peripheral lumens 864 surrounding acentral lumen 868. Central lumen 868 may be left open as a workingchannel of articulated structure 850, to allow the articulated structureto be advanced over a guidewire, for advancing a guidewire or toolthrough the articulated structure, or the like. An array 870 ofeccentric balloons 872 is distributed axially and circumferentiallyabout the multi-lumen core, with the array again taking the form of anM×N array, with M subsets of balloons being distributedcircumferentially, each of the M subsets being aligned along a lateralbending orientation (M here being 4, with alternative embodiments having1, 2, 3, or other numbers of circumferential subsets as describedabove). Each of the M subsets includes N balloons, with N typicallybeing from 1 to 20. The N balloons of each subset may be in fluidcommunication with an associated peripheral lumen 864 so that they canbe inflated as a group. Eccentric balloons 872 may optionally be formedby drilling ports between selected peripheral lumens 864 to the outersurface of the body of the core, and by affixing a tube of balloon wallmaterial affixed over the drilled body of multi-lumen core 862, with theinner surface of the balloon tube being sealingly affixed to an outersurface of the multi-lumen body of the core. Alternatively, eccentricballoons may be integral with the multi-lumen core structure, forexample, with the balloons being formed by locally heating anappropriate region of the multi-lumen core and pressurizing anunderlying lumen of the core to locally blow the material of themulti-lumen body of the core radially outwardly to form the balloons.Regardless, the balloons extend laterally from the body of themulti-lumen core, with the balloons optionally comprising compliantballoons, semi-compliant balloons, or non-compliant balloons. The shapeof the inflated balloons may be roughly spherical, hemispherical, kidneyshaped (curving circumferentially about the axis of the core),cylindrical (typically with a length:diameter aspect ratio of less than3:1, with the length extending radially or circumferentially), or somecombination of two or more of these.

When multi-lumen core 862 is assembled with frame 856 (as in FIGS. 29A,29C, and 29D), the body of the multi-lumen core is received in the lumenof the frame and balloons 872 are disposed between the apposed surfacesof loops 858. By selectively inflating one subset of balloons 872aligned along one of the lateral bending orientations, and byselectively deflating the opposed subset of balloons (offset from theinflated balloons by about 180 degrees), the axis of articulatablestructure 850 can be curved. Controlling inflation pressures of theopposed balloon subsets may vary both a curvature and a stiffness ofarticulatable structure 850, with increasing opposed inflation pressuresincreasing stiffness and decreasing opposed inflation pressuresdecreasing stiffness. Varying inflation of the laterally offset balloonsets (at 90 and 270 degrees about the axis, for example) may similarlyvariably curve the structure in the orthogonal bending orientation andcontrol stiffness in that direction.

As can be understood with reference to FIG. 29E, the profile of thesingle-core assembly may be quite small, with an exemplary embodimenthaving an outer diameter 874 of frame 856 at about 1.4 mm, an outerdiameter 876 of the body of multi-lumen core 862 of about 0.82 mm, andan inner diameter 878 of the peripheral lumens 864 of about 0.10 mm. Themulti-lumen core body and balloons may comprise polymers, such as any ofthe extrusion or balloons materials described above, and the frame maycomprise a polymer or metal structure, the frame optionally being formedby molding, cutting lateral incisions in a tube of material, 3Dprinting, or the like. Note that the exemplary multi-lumen corestructure includes 8 peripheral lumens while the illustrated segmentmakes use of 4 lumens to articulate the segment in two degrees offreedom; a second segment may be axially coupled with the shown segmentto provide additional degrees of freedom, and more lumens may beprovided when still further segments are to be included.

While the exemplary embodiment have been described in some detail forclarity of understanding and by way of example, a variety ofmodifications, changes, and adaptations of the structures and methodsdescribed herein will be obvious to those of skill in the art. Hence,the scope of the present invention is limited solely by the claimsattached hereto.

As can be understood from the disclosure herein, and referring firstFIGS. 15 and 24E, the articulated structures disclosed herein maycomprise a multi-lumen helical shaft 908. Referring to FIG. 5A, thearticulation balloons will often define an array 910, which may comprisesub-arrays such as a first array 912 and a second array 914. Referringto FIGS. 1 and 2, an articulated portion 20 of a catheter 12 may includea first segment 902, a second segment 904, and a third segment 906.Referring to FIG. 24C, a plurality of balloons may be defined in-part bya continuous balloon wall tube 916 having balloon cross-section regions918 and seal cross-section regions 920. Referring to FIG. 24E-3, areinforcement band 922 may reinforce the balloon/shaft seal. Referringto FIG. 29C, the frame may comprise a series of loops 858 interconnectedby axial struts 860. Referring to FIG. 6P, the balloons may be disposedbetween pairs of interface regions 924 defined by the elongate frame.Referring to FIG. 11E, the balloon tube may have balloon regions 926,and the helical multi-lumen shaft and balloon tube may define a helix928, with the helical assembly including a helical shaft 930 and aballoon wall tube 932.

What is claimed is:
 1. An articulatable body comprising: a multi-lumenhelical shaft having a proximal end, a distal end, and an axistherebetween, the shaft defining an axial series of loops, including afirst loop and a second loop, and having a plurality of lumens includinga first lumen and a second lumen, the lumens being helical so as to windhelically with the loops; a plurality of balloons distributed along theloops such that a first subset of the plurality of balloons isdistributed along the first loop and a second subset of the plurality ofballoons is distributed along the second loop, the first subset ofballoons including a balloon offset from the axis along a first lateralorientation and a balloon offset from the axis along a second lateralorientation, the second lateral orientation offset circumferentiallyfrom the first lateral orientation, the second subset of balloonsincluding a balloon offset from the axis along the first lateralorientation and a balloon offset from the axis along the second lateralorientation, each balloon having a balloon wall extending around theshaft; and a plurality of ports opening into the shaft, each portproviding fluid communication between an associated balloon and anassociated lumen, the ports providing fluid communication between thefirst lumen and the balloon of the first subset of balloons offset fromthe axis along the first lateral orientation and the balloon of thesecond subset of balloons offset from the axis along the first lateralorientation so that pressure in the first lumen induces bending of theaxis away from the first lateral orientation, the ports also providingfluid communication between the second lumen and the balloon of thefirst subset of balloons offset from the axis along the second lateralorientation and the balloon of the second subset of balloons offset fromthe axis along the second lateral orientation so that pressure in thesecond lumen induces bending of the axis away from the second lateralorientation, the pressure in the second lumen being independent of thepressure in the first lumen.
 2. The articulatable body of claim 1,wherein the plurality of balloons define an M×N array, with M lateralsubsets of the plurality of balloons being distributed circumferentiallyabout the axis, each of the M lateral subsets including N balloonsaligned along an associated lateral bending orientation.
 3. Thearticulatable body of claim 2, wherein M is three or four so that thereare three or four lateral subsets of balloons, and wherein the portsassociated with the plurality of balloons of the M lateral subsetsprovide fluid communication between N balloons and an associated lumen,such that each of the lateral orientations has an associated lumen ofthe shaft.
 4. The articulatable body of claim 3, wherein the arraycomprises a first array extending along a first segment of thearticulatable body, the first segment configured to be driven in aplurality of degrees of freedom by fluid transmitted along lumensassociated with the M lateral subsets, and further comprising a secondsegment of the articulatable body axially offset from the first segment,the second segment having a second array and configured to be driven ina plurality of degrees of freedom by fluid transmitted along lumens ofthe shaft associated with the second array.
 5. The articulatable body ofclaim 1, wherein the balloon walls comprise a semi-compliant ornon-compliant balloon wall material.
 6. The articulatable body of claim1, wherein the plurality of balloons comprise a continuous balloon walltube sealingly affixed around the shaft at a plurality of seals, theseals being separated along the shaft axis so that the balloon wall tubedefines the balloon walls of the plurality of balloons.
 7. Thearticulatable body of claim 6, wherein the balloon wall tube has aplurality of balloon cross-section regions interleaved with a pluralityof seal cross-section regions, the balloon cross-section regions beinglarger than the seal cross-section regions to facilitate fluid expansionof the plurality of balloons away from the shaft.
 8. The articulatablebody of claim 6, further comprising a reinforcement band disposed overthe balloon adjacent a seal of the plurality of seals so as to inhibitseparation of the plurality of balloons from the shaft associated withinflation of the plurality of balloons.
 9. The articulatable body ofclaim 1, further comprising an elongate structural skeleton supportingthe multi-lumen shaft, the skeleton having pairs of primarily axiallyoriented interface regions separated by axial offsets, the offsetschanging with flexing of the skeleton, wherein the plurality of balloonsare disposed between the regions of the pairs.
 10. The articulatablebody of claim 1, wherein the articulatable body comprises a catheter,the distal end being configured for insertion into a body of a patient.11. An articulatable body comprising: a multi-lumen helical shaft havinga proximal end, a distal end, and an axis therebetween, the shaftdefining an axial series of loops, including a first loop and a secondloop, and having a plurality of lumens including a first lumen and asecond lumen, the lumens extending helically with the loops; a pluralityof balloons distributed along the loops such that a first subset of theplurality of balloons is distributed along and circumferentially offsetaround the first loop and a second subset of the plurality of balloonsis distributed along and circumferentially offset around the secondloop, each balloon having a balloon wall extending around the shaft; anda plurality of ports opening into the shaft, each port providing fluidcommunication between an associated balloon and an associated lumen;wherein a third subset of the plurality of balloons is offset from theaxis and aligned along a first lateral bending orientation, wherein afourth subset of the plurality of balloons is aligned along a secondlateral bending orientation offset from the axis and offset from thefirst lateral orientation; and wherein the ports associated with thethird subset of balloons are in fluid communication with the firstlumen, and wherein the ports associated with the fourth subset ofballoons are in fluid communication with the second lumen.
 12. Thearticulatable body of claim 11, wherein a plurality of additionalsubsets of balloons is distributed along other loops, wherein the thirdsubset and the fourth subset include balloons of the first subset, thesecond subset, and the additional subsets, wherein a fifth subset of theplurality of balloons is offset from the axis and aligned along a thirdlateral bending orientation offset from the first lateral orientationand the second lateral orientation, the third subset, the fourth subset,and the fifth subset each being aligned primarily axially, the firstsubset, the second subset, and the additional subsets each being alignedprimarily circumferentially.
 13. An articulatable body comprising: anelongate flexible skeleton having a proximal end and a distal end anddefining an axis therebetween, the skeleton having pairs of interfaceregions separated by offsets, the interface regions being primarilyaxial and the offsets extending along the axis, the offsets changingwith flexing of the skeleton; a substrate supported by the skeleton,wherein the substrate comprises a helical multi-lumen shaft having aplurality of helical lumens winding around and offset from the axis; anda plurality of balloons supported by the substrate, the plurality ofballoons distributed axially and circumferentially about the skeletonand disposed between and coupled with pairs of interface regions so thatinflation of each balloon urges the pairs of interface regions axiallyapart, wherein the plurality of balloons comprises an M×N array ofballoons supported by the substrate, M being three or four such thatthree or four subsets of balloons are distributed circumferentiallyabout the axis, each subset aligned along an associated lateral bendingorientation offset from the axis, N being two or more such that each ofthe three or four subsets of balloons includes two or more axiallyseparated balloons, a channel system disposed in the substrate so as toprovide fluid communication between the proximal end of the skeleton andthe plurality of balloons, the channel system comprising M lumens of thehelical multi-lumen shaft, each lumen in fluid communication with thetwo or more axially separated balloons so as to have a balloon inflationpressure independent of the other lumens.
 14. The articulatable body ofclaim 13, wherein the substrate has a first opposed major surface and asecond opposed major surface and a plurality of layers extending alongthe first opposed major surface and the second opposed major surface,the channel system being sealed between layers of the substrate.
 15. Thearticulatable body of claim 14, wherein the substrate is curved in acylindrical shape, and wherein a plurality of valves is disposed alongchannels so as to provide selective fluid communication between theproximal end and the plurality of balloons.
 16. The articulatable bodyof claim 14, wherein the plurality of balloons have balloon walls thatare integral with a first layer of the substrate.
 17. The articulatablebody of claim 13, wherein the substrate comprises a single multi-lumenshaft, and wherein the frame comprises a tubular structure having loopsseparated by axial struts, the pairs of regions comprising opposingsurfaces of the loops.
 18. A method for making an articulatablestructure, the method comprising: providing a multi-lumen shaft having aproximal end and a distal end with a shaft axis therebetween, aplurality of lumens extending along the shaft axis, the plurality oflumens including a first lumen and a second lumen; forming ports intothe lumens, the ports being disposed within a plurality of balloonregions, the balloon regions separated along the shaft axis; providing aballoon wall tube having a proximal end and a distal end with a lumenextending therebetween; and sealing the shaft within the lumen of theballoon wall tube at a plurality of seals between the balloon regions soas to form a plurality of balloons including a first subset of theplurality of balloons inflatable to a first pressure via the first lumenand a second subset of the plurality of balloons inflatable to a secondpressure independent of the first pressure via the second lumen forbending of the axis of the articulatable structure along differentlateral bending orientations; wherein the shaft axis comprises a helixhaving a plurality of loops, the plurality of lumens comprising helicallumens extending along the loops, and wherein the plurality of balloonsare disposed on a plurality of separate loops.
 19. The method of claim18, wherein the shaft axis is straight during the sealing of the shaftwithin the lumen of the balloon wall tube, and further comprisingbending the shaft within the balloon tube to form a helical shaft.
 20. Amethod for articulating an articulatable body, the method comprising:transmitting fluid along a plurality of lumens of a helical multi-lumenshaft, the shaft defining a series of loops and the plurality of lumensextending helically along the loops, the loops including a first loopand a second loop; and inflating a plurality of balloons with thetransmitted fluid so as to laterally bend or elongate the shaft, theplurality of balloons distributed along the loops such that a firstsubset of the plurality of balloons is distributed along the first loopand a second subset of the plurality of balloons is distributed alongthe second loop, each balloon having a balloon wall extending around theshaft so the shaft is surrounded by the balloon wall, the inflating ofthe plurality of balloons performed by directing the fluid radially fromthe plurality of lumens through a plurality of ports so that each portprovides fluid communication between an associated lumen and anassociated balloon; wherein the inflating of the plurality of balloonsis performed using independent pressures within the lumens so as to movea tool supported by the articulatable body in a plurality of degrees offreedom, the tool offset from the plurality of balloons.
 21. The methodof claim 20, wherein the articulatable body has a proximal end and adistal end with an axis therebetween, wherein the plurality of lumensinclude a first lumen and a second lumen, and wherein the first subsetof balloons includes a balloon offset from the axis along a firstlateral orientation and the second subset of balloons includes a balloonoffset from the axis along the first lateral orientation, wherein theinflating of the balloon offset from the axis along the first lateralorientation is performed by controlling pressure in the first lumen. 22.The method of claim 21, wherein the first subset of balloons includes aballoon offset from the axis along a second lateral orientation, thesecond lateral orientation offset circumferentially from the firstlateral orientation, wherein the second subset of balloons includes aballoon offset from the axis along the second lateral orientation,wherein the inflating of the balloon offset from the axis along thesecond lateral orientation is performed by controlling pressure in thesecond lumen, the pressure in the second lumen being independent of thepressure in the first lumen.
 23. The method of claim 22, wherein theinflating of the plurality of balloons is performed so that pressure inthe first lumen induces bending of the axis away from the first lateralorientation and so that pressure in the second lumen induces bending ofthe axis away from the second lateral orientation.
 24. The method ofclaim of claim 22, wherein the inflating of the plurality of balloons isperformed so as to axially elongate the articulatable body by increasingthe pressure in the first lumen and the second lumen.
 25. The method ofclaim 20, wherein the tool is distal of the plurality of balloons andwherein the inflating of the plurality of balloons is performed so as tomove the tool with at least 3 degrees of freedom.